Radio-frequency isolation using backside cavities

ABSTRACT

A method for fabricating a semiconductor device involves providing a transistor device formed over an oxide layer formed on a semiconductor substrate, removing at least part of the semiconductor substrate, applying an interface material below to at least a portion of the oxide layer, removing a portion of the interface material to form a trench, and at least partially covering the interface material and the trench with a substrate layer to form a cavity

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.15/833,175, filed Dec. 6, 2017, and entitled CAVITY FORMATION INBACKSIDE INTERFACE LAYER FOR RADIO-FREQUENCY ISOLATION, which is acontinuation of U.S. patent application Ser. No. 15/154,817, filed May13, 2016, and entitled BACKSIDE CAVITY FORMATION IN SEMICONDUCTORDEVICES, which claims priority to U.S. Provisional Application No.62/162,643, filed May 15, 2015, and entitled CAVITY FORMATION INSEMICONDUCTOR DEVICES, the disclosures of which are hereby incorporatedby reference in their entirety.

BACKGROUND Field

The present disclosure relates to field-effect transistor (FET) devicessuch as silicon-on-insulator (SOI) devices.

Description of the Related Art

In electronics applications, field-effect transistors (FETs) can beutilized as switches. Such switches can allow, for example, routing ofradio-frequency (RF) signals in wireless devices.

SUMMARY

In accordance with a number of implementations, the present disclosurerelates to a method for fabricating a radio-frequency (RF) device. Themethod may comprise providing a field-effect transistor (FET) formedover an oxide layer formed on a semiconductor substrate, removing atleast part of the semiconductor substrate to expose at least a portionof a backside of the oxide layer, applying a sacrificial material to thebackside of the oxide layer, and applying an interface material to atleast a portion of the backside of the oxide layer, the interfacematerial at least partially covering the sacrificial material. Themethod may further comprise removing at least a portion of thesacrificial material to form a cavity at least partially covered by theinterface layer.

In certain embodiments, the method further comprises applying asubstrate contact layer to the backside of the oxide layer, thesubstrate contact layer being at least partially exposed in the cavityafter said removing the at least a portion of the sacrificial material.The method may further comprise applying a replacement substrate layerto the interface layer to provide mechanical stability for the RFdevice.

In certain embodiments, applying the sacrificial material involvesforming a channel of the sacrificial material leading to a die boundaryassociated with the RF device. Removing the at least a portion of thesacrificial material may be performed at least partially through thechannel. In certain embodiments, removing the at least a portion of thesacrificial material involves evaporating the at least a portion of thesacrificial material. The method may further comprise removing a handlewafer from a front-side of a passivation layer disposed over the FET.The sacrificial material may comprise nitride, for example.

In accordance with a number of implementations, the present disclosurerelates to a radio-frequency (RF) device comprising a field-effecttransistor (FET) implemented over an oxide layer, a patterned form ofsacrificial material disposed on a backside of the oxide layer, and aninterface layer covering at least a portion of the backside of the oxidelayer and the sacrificial material.

In certain embodiments, the form of sacrificial material includes achannel leading to an edge of a die associated with the RF device. Theform of sacrificial material may be patterned to allow for removal ofthe sacrificial material through evaporation by applying heat to thechannel.

In certain embodiments, the RF device further comprises a substratecontact layer disposed on the backside of the oxide layer in physicalcontact with the form of sacrificial material. The RF device maycomprise a replacement substrate layer applied to the interface layer,the replacement providing mechanical stability for the RF device. Incertain embodiments, the patterned form of sacrificial material includesa channel leading to a die boundary associated with the RF device. TheFET may be part of a switching device. In certain embodiments, thesacrificial material comprises low-density oxide.

In accordance with a number of implementations, the present disclosurerelates to a wireless device comprising a transceiver configured toprocess radio-frequency (RF) signals and an RF module in communicationwith the transceiver, the RF module including a switching device havinga field-effect transistor (FET) implemented over an oxide layer, theswitching device including a patterned form of sacrificial materialdisposed on a backside of the oxide layer, the switching device furtherincluding an interface layer covering at least a portion of the backsideof the oxide layer and the sacrificial material. The wireless devicefurther comprises an antenna in communication with the RF module, theantenna configured to facilitate transmitting and/or receiving of the RFsignals.

In certain embodiments, the RF module further includes a replacementsubstrate layer applied to the interface layer. The patterned form ofsacrificial may include a channel leading to a die boundary associatedwith the RF module. The channel may be dimensioned to allow for removalof at least a portion of the sacrificial material through evaporationthrough the channel.

In accordance with a number of implementations, the present disclosurerelates to a radio-frequency (RF) module comprising a packagingsubstrate configured to receive a plurality of devices and a switchingdevice mounted on the packaging substrate, the switching deviceincluding a field-effect transistor (FET) implemented over an oxidelayer, the switching device further including a patterned form ofsacrificial material disposed on a backside of the oxide layer, theswitching device further including an interface layer covering at leasta portion of the backside of the oxide layer and the sacrificialmaterial.

In accordance with a number of implementations, the present disclosurerelates to a method for fabricating a radio-frequency (RF) device. Themethod comprises providing a field-effect transistor (FET), forming oneor more electrical connections to the FET, forming one or moredielectric layers over at least a portion of the electrical connections,and disposing an electrical element over the one or more dielectriclayers, the electrical element being in electrical communication withthe FET via the one or more electrical connections. The method furthercomprises covering at least a portion of the electrical element with asacrificial material, applying an interface material over the one ormore dielectric layers, the interface material at least partiallycovering the sacrificial material, and removing at least a portion ofthe sacrificial material to form a cavity at least partially covered bythe interface layer.

The electrical element may be a surface acoustic wave (SAW) device, abulk acoustic wave (BAW) device, or other type of electrical device,such as a passive device (e.g., inductor). The method may furthercomprise applying a handle wafer to a top surface of the interface layerto provide mechanical stability for the RF device.

In certain embodiments, the FET is formed over an oxide layer formed ona semiconductor substrate. The method may comprise at least partiallyremoving the semiconductor substrate thereby exposing at least a portionof a backside of the oxide layer. The method may further comprisedisposing an electrical contact structure on the backside of the oxidelayer to provide electrical contact to the one or more electricalconnections via a through-oxide via.

Covering the at least a portion of the electrical element with thesacrificial material may involve forming a channel of the sacrificialmaterial leading to a die boundary associated with the RF device.Removing the at least a portion of the sacrificial material may beperformed at least partially through the channel. Removing the at leasta portion of the sacrificial material may involve evaporating the atleast a portion of the sacrificial material.

In accordance with a number of implementations, the present disclosurerelates to a radio-frequency (RF) device comprising a field-effecttransistor (FET) implemented over an oxide layer, one or more electricalconnections to the FET, one or more dielectric layers formed over atleast a portion of the electrical connections, and an electrical elementdisposed over the one or more dielectric layers, the electrical elementbeing in electrical communication with the FET via the one or moreelectrical connections. The RF device further comprises a patterned formof sacrificial material covering at least a portion of the electricalelement and an interface layer covering at least a portion of the one ormore dielectric layers and the sacrificial material.

The electrical element may be a surface acoustic wave (SAW) device, abulk acoustic wave (BAW) device, or other type of electrical device,such as a passive device (e.g., inductor). The RF device may comprise ahandle wafer applied to a top surface of the interface layer, the handlewafer providing mechanical stability for the RF device.

The FET may be formed over an oxide layer. In certain embodiments, theRF device comprises an electrical contact structure disposed on abackside of the oxide layer that provides electrical contact to the oneor more electrical connections via a through-oxide via through the oxidelayer. The patterned form of sacrificial material may include a channelleading to a die boundary associated with the RF device. The channel maybe designed such that the at least a portion of the sacrificial materialmay be removed at least partially through the channel. In certainembodiments, the sacrificial material is configured to be evaporated toform a cavity.

In accordance with a number of implementations, the present disclosurerelates to a wireless device comprising a transceiver configured toprocess radio-frequency (RF) signals, and an RF module in communicationwith the transceiver, the RF module including a switching device havinga field-effect transistor (FET) implemented over an oxide layer, theswitching device further including one or more electrical connections tothe FET, one or more dielectric layers formed over at least a portion ofthe electrical connections, an electrical element disposed over the oneor more dielectric layers that is electrically coupled to the FET viathe one or more electrical connections, a patterned form of sacrificialmaterial covering at least a portion of the electrical element, and aninterface layer covering at least a portion of the one or moredielectric layers and the sacrificial material. The wireless devicefurther comprises an antenna in communication with the RF module, theantenna configured to facilitate transmitting and/or receiving of the RFsignals.

In accordance with a number of implementations, the present disclosurerelates to a method for fabricating a radio-frequency (RF) device. Themethod comprises providing a field-effect transistor (FET), forming oneor more electrical connections to the FET, forming one or moredielectric layers over at least a portion of the electrical connections,applying a form of sacrificial material over a portion of the one ormore dielectric layers at least partially above the FET, and applying aninterface material over the one or more dielectric layers, the interfacematerial at least partially covering the sacrificial material. Themethod further comprises removing at least a portion of the sacrificialmaterial to form a cavity at least partially covered by the interfacelayer.

In certain embodiments, the method further comprises applying a handlewafer to a top surface of the interface layer to provide mechanicalstability for the RF device. The FET may be formed over an oxide layerformed on a semiconductor substrate. In certain embodiments, the methodfurther comprises at least partially removing the semiconductorsubstrate, thereby exposing at least a portion of a backside of theoxide layer. The method may further comprise disposing an electricalcontact structure on the backside of the oxide layer to provideelectrical contact to the one or more electrical connections via athrough-oxide via. In certain embodiments, removing the at least aportion of the sacrificial material involves evaporating the at least aportion of the sacrificial material.

In accordance with a number of implementations, the present disclosurerelates to a method for fabricating a radio-frequency (RF) device. Themethod comprises providing a field-effect transistor (FET), forming oneor more electrical connections to the FET, forming one or moredielectric layers over at least a portion of the electrical connections,and disposing an electrical element at least partially above the one ormore dielectric layers, the electrical element being in electricalcommunication with the FET via the one or more electrical connections.The method further comprises applying an interface material over atleast a portion of the one or more dielectric layers, removing at leasta portion of the interface material to form a trench above at least aportion of the electrical element, and covering at least a portion ofthe interface material and the trench with a substrate layer to form acavity, the electrical element being disposed at least partially withinthe cavity.

The electrical element may be a surface acoustic wave (SAW) device, abulk acoustic wave (BAW) device, or other type of electrical device,such as a passive device. In certain embodiments, the electrical elementis an inductor. The FET may be formed over a semiconductor substrate andan oxide layer formed on the semiconductor substrate. The method mayfurther comprise at least partially removing the semiconductor substratethereby exposing at least a portion of a backside of the oxide layer.The method may further comprising disposing an electrical contactstructure on the backside of the oxide layer to provide electricalcontact to the one or more electrical connections via a through-oxidevia.

In accordance with a number of implementations, the present disclosurerelates to a radio-frequency (RF) device comprising a field-effecttransistor (FET) implemented over an oxide layer, one or more electricalconnections to the FET, one or more dielectric layers formed over atleast a portion of the electrical connections, and an electrical elementdisposed over the one or more dielectric layers, the electrical elementbeing in electrical communication with the FET via the one or moreelectrical connections. The RF device further comprises an interfacelayer covering at least a portion of the one or more dielectric layers,the interface layer having a trench therein above at least a portion ofthe electrical element, and a substrate layer covering at least aportion of the interface layer and the trench to form a cavity, theelectrical element being disposed at least partially within the cavity.

The electrical element may be a surface acoustic wave (SAW) device, abulk acoustic wave (BAW) device, or other type of electrical device,such as a passive device. In certain embodiments, the FET is formed overan oxide layer.

In accordance with a number of implementations, the present disclosurerelates to a wireless device comprising a transceiver configured toprocess radio-frequency (RF) signals, and an RF module in communicationwith the transceiver, the RF module including a switching device havinga field-effect transistor (FET) implemented over an oxide layer, theswitching device further including one or more electrical connections tothe FET, one or more dielectric layers formed over at least a portion ofthe electrical connections, an electrical element disposed over the oneor more dielectric layers that is electrically coupled to the FET viathe one or more electrical connections, an interface layer covering atleast a portion of the one or more dielectric layers and having a trenchtherein above the at least a portion of the electrical element, and asubstrate layer covering at least a portion of the interface layer andthe trench to form a cavity, the electrical element being disposed atleast partially within the cavity. The wireless device further comprisesan antenna in communication with the RF module, the antenna configuredto facilitate transmitting and/or receiving of the RF signals.

In accordance with a number of implementations, the present disclosurerelates to a method for fabricating a radio-frequency (RF) device. Themethod comprises providing a field-effect transistor (FET), forming oneor more electrical connections to the FET, forming one or moredielectric layers over at least a portion of the electrical connections,applying an interface material over at least a portion of the one ormore dielectric layers, removing at least a portion of the interfacematerial to form a trench at least partially above the FET, and coveringat least a portion of the interface material and the trench with asubstrate layer to form a cavity at least partially above the FET.

The FET may be formed over a semiconductor substrate and an oxide layerformed on the semiconductor substrate. In certain embodiments, themethod further comprises at least partially removing the semiconductorsubstrate, thereby exposing at least a portion of a backside of theoxide layer. In certain embodiments, the method comprises disposing anelectrical contact structure on the backside of the oxide layer toprovide electrical contact to the one or more electrical connections viaa through-oxide via.

In accordance with a number of implementations, the present disclosurerelates to a method for fabricating a radio-frequency (RF) device. Themethod comprises providing a field-effect transistor (FET) formed overan oxide layer formed on a semiconductor substrate, removing at leastpart of the semiconductor substrate to expose at least a portion of abackside of the oxide layer, applying an interface material to at leasta portion of the backside of the oxide layer, removing at least aportion of the interface material to form a trench, and covering atleast a portion of the interface material and the trench with asubstrate layer to form a cavity.

In certain embodiments, the method further comprises applying asubstrate contact layer to at least a portion of the backside of theoxide layer, the substrate contact layer being at least partiallyexposed in the cavity after said covering the at least a portion of theinterface material and the trench. The substrate contact layer may beelectrically coupled to the FET via a through-oxide via.

In certain embodiments, the method comprises removing a handle waferfrom a top-side of a passivation layer disposed above the FET. Forexample, the passivation layer may be one of one or more dielectriclayers formed over electrical connections to the FET. In certainembodiments, the trench is at least partially below the FET. The trenchmay be at least partially below an electrical device coupled to the FETvia one or more electrical connections formed in one or more dielectriclayers formed over the FET. In certain embodiments, removing the atleast a portion of the interface material comprises etching away the atleast a portion of the interface material.

In accordance with a number of implementations, the present disclosurerelates to a radio-frequency (RF) device comprising a field-effecttransistor (FET) implemented over an oxide layer, an interface layerapplied to at least a portion of a backside of the oxide layer, theinterface layer having a trench formed therein, and a substrate layercovering at least a portion of the interface layer and the trench toform a cavity.

In certain embodiments, the RF device comprises a substrate contactlayer applied to at least a portion of the backside of the oxide layer,the substrate contact layer being at least partially exposed in thecavity. The substrate contact layer may be electrically coupled to theFET via a through-oxide via. The RF device may comprise one or moredielectric layers formed over electrical connections to the FET. Incertain embodiments, the trench is at least partially below the FET. Thetrench may be at least partially below an electrical device coupled tothe FET via one or more electrical connections formed in one or moredielectric layers formed over the FET.

In accordance with a number of implementations, the present disclosurerelates to a wireless device comprising a transceiver configured toprocess radio-frequency (RF) signals, and an RF module in communicationwith the transceiver, the RF module including a switching device havinga field-effect transistor (FET) implemented over an oxide layer, aninterface layer applied to at least a portion of a backside of the oxidelayer, the interface layer having a trench formed therein, and asubstrate layer covering at least a portion of the interface layer andthe trench to form a cavity. The wireless device further comprises anantenna in communication with the RF module, the antenna configured tofacilitate transmitting and/or receiving of the RF signals.

The RF module may include a substrate contact layer applied to at leasta portion of the backside of the oxide layer, the substrate contactlayer being at least partially exposed in the cavity. The substratecontact layer may be electrically coupled to the FET via a through-oxidevia.

In certain embodiments, the switching device includes one or moredielectric layers formed over electrical connections to the FET. Incertain embodiments, the trench is at least partially below the FET. Thetrench may be at least partially below an electrical device coupled tothe FET via one or more electrical connections formed in one or moredielectric layers formed over the FET.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of a field-effect transistor (FET) device havingan active FET implemented on a substrate, and a region below the activeFET configured to include one or more features to provide one or moredesirable operating functionalities for the active FET.

FIG. 2 shows an example of a FET device having an active FET implementedon a substrate, and a region above the active FET configured to includeone or more features to provide one or more desirable operatingfunctionalities for the active FET.

FIG. 3 shows that in some embodiments, a FET device can include both ofthe regions of FIGS. 1 and 2 relative an active FET.

FIG. 4 shows an example FET device implemented as an individualsilicon-on-insulator (SOI) unit.

FIG. 5 shows that in some embodiments, a plurality of individual SOIdevices similar to the example SOI device of FIG. 4 can be implementedon a wafer.

FIG. 6A shows an example wafer assembly having a first wafer and asecond wafer positioned over the first wafer.

FIG. 6B shows an unassembled view of the first and second wafers of theexample of FIG. 6A.

FIG. 7 shows a terminal representation of an SOI FET having nodesassociated with a gate, a source, a drain, a body, and a substrate.

FIGS. 8A and 8B show side sectional and plan views, respectively, of anexample SOI FET device having a node for its substrate.

FIG. 9 shows a side sectional view of an SOI substrate that can beutilized to form an SOI FET device having an electrical connection for asubstrate layer.

FIG. 10 shows a side sectional view of an SOI FET device having anelectrical connection for a substrate layer.

FIG. 11 shows an example SOI FET device that is similar to the exampleof FIG. 10, but in which a trap-rich layer is substantially absent.

FIG. 12 shows that in some embodiments, an electrical connection to asubstrate can be implemented without being coupled to other portions ofan active FET.

FIG. 13 shows that in some embodiments, a handle wafer can include aplurality of doped regions implemented to provide one or morefunctionalities similar to a trap-rich interface layer in the example ofFIG. 10.

FIGS. 14A and 14B show side sectional and plan views of an example SOIFET having a contact layer implemented underneath an insulator layersuch as a buried oxide (BOX) layer.

FIG. 15 shows an example SOI FET device that is similar to the exampleof FIG. 11, but with a contact layer implemented underneath a BOX layer.

FIG. 16 shows an example SOI FET device that is similar to the exampleof FIG. 12, but with a contact layer implemented underneath a BOX layer.

FIG. 17 shows an example SOI FET device that is similar to the exampleof FIG. 10, but with a contact layer implemented underneath a BOX layer.

FIG. 18 shows an example SOI FET device that is similar to the exampleof FIG. 13, but with a contact layer implemented underneath a BOX layer.

FIG. 19 shows another example SOI FET device that is similar to theexample of FIG. 13, but with a perforated contact layer implementedunderneath a BOX layer.

FIG. 20 shows a process that can be implemented to facilitatefabrication of an SOI FET device having one or more features asdescribed herein.

FIG. 21 shows examples of various stages of the fabrication process ofFIG. 20.

FIGS. 22A and 22B show a process that can be implemented to fabricate anSOI FET device having one or more features as described herein.

FIGS. 23A and 23B show examples of various stages of the fabricationprocess of FIGS. 22A and 22B.

FIG. 24 shows that in some embodiments, a contact layer having one ormore features as described herein can be implemented with, for example,desired dimensions and/or separation from an active FET to provide oneor more functionalities.

FIGS. 25A and 25B show examples of how a contact layer having one ormore features as described herein can be dimensioned to provide one ormore desirable functionalities.

FIGS. 26A-26F show non-limiting examples of how contact layers can beimplemented relative to circuit elements.

FIG. 27 shows an example of a contact layer that can be implemented inthe example SOI FET device of FIG. 19.

FIG. 28 shows that in some embodiments, an SOI FET device can have itscontact layer having one or more features as described herein biased by,for example, a substrate bias network.

FIG. 29 shows an example of a radio-frequency (RF) switchingconfiguration having an RF core and an energy management (EM) core.

FIG. 30 shows an example of the RF core of FIG. 29, in which each of theswitch arms includes a stack of FET devices.

FIG. 31 shows an example of the biasing configuration of FIG. 28,implemented in a switch arm having a stack of FETs as described inreference to FIG. 30.

FIG. 32 shows that a pattern of one or more conductive layers can beimplemented to be electrically connected to a bias circuit such as asubstrate bias circuit.

FIG. 33 shows an example configuration in which a pattern of one or moreconductive layers can generally form a ring shaped perimetersubstantially around an entire die having an RF core and an energymanagement core (“EM core”).

FIG. 34 shows an example configuration in which a pattern of one or moreconductive layers can generally form a ring shaped distributionimplemented substantially around each of an RF core and an EM core of aswitching die.

FIG. 35 shows an example configuration in which a pattern of one or moreconductive layers can generally form a ring shaped distributionimplemented substantially around an assembly of series arms and shuntarms.

FIG. 36 shows an example configuration in which a pattern of one or moreconductive layers can generally form a ring shaped distributionimplemented substantially around each of series arms and shunt arms.

FIG. 37 shows an example configuration in which a pattern of one or moreconductive layers can generally form a ring shaped distributionimplemented substantially around each FET in a given arm.

FIGS. 38A-38E show non-limiting examples of patterns of one or moreconductive layers that can be implemented around a circuit element.

FIGS. 39A and 39B show that in some embodiments, there may be more thanone pattern of one or more conductive layers implemented relative acircuit element.

FIG. 40 shows an example in which a conductive layer of an SOI FETdevice can be electrically connected to a substrate bias network.

FIG. 41 shows another example in which a conductive layer of an SOI FETdevice can be electrically connected to a substrate bias network.

FIG. 42 shows an example in which a conductive layer of an SOI FETdevice can be electrically connected to a gate node of the SOI FETdevice.

FIG. 43 shows an example in which a conductive layer of an SOI FETdevice can be electrically connected to a gate node of the SOI FETdevice through a phase-shift circuit.

FIG. 44 shows an example in which a conductive layer of an SOI FETdevice can be electrically connected to a gate node of the SOI FETdevice through a phase-shift circuit, similar to the example of FIG. 43,and in which a substrate bias network can be configured to allowapplication of a DC control voltage to the conductive layer.

FIG. 45A shows an example that is similar to the example of FIG. 42, butwith a diode D in series with a resistance R.

FIG. 45B shows that in some embodiments, the polarity of the diode D canbe reversed from the example of FIG. 45A.

FIG. 46 shows an example that is similar to the example of FIG. 43, butwith a diode D in parallel with a phase-shifting circuit.

FIG. 47 shows an example that is similar to the example of FIG. 42, butwith a diode D in series with a resistance R.

FIG. 48 shows an example that is similar to the example of FIG. 46, butwith biasing.

FIG. 49 shows an SOI FET device having a conductive layer as describedherein.

FIGS. 50A-50D show examples of how a conductive layer of an SOI FETdevice can be coupled to other nodes of the SOI FET device.

FIGS. 51A-51D show examples of how a conductive layer of an SOI FETdevice can be coupled to other nodes of the SOI FET device through aphase-shifting circuit.

FIGS. 52A-52D show examples that are similar to the examples of FIGS.50A-50D, and in which a bias signal can be applied to the conductivelayer.

FIGS. 53A-53D show examples that are similar to the examples of FIGS.51A-51D, and in which a bias signal can be applied to the conductivelayer.

FIGS. 54A-54D show examples of how a conductive layer of an SOI FETdevice can be coupled to other nodes of the SOI FET device through adiode D.

FIGS. 55A-55D show examples of how a conductive layer of an SOI FETdevice can be coupled to other nodes of the SOI FET device through adiode D and a phase-shifting circuit.

FIGS. 56A-56D show examples that are similar to the examples of FIGS.54A-54D, and in which a bias signal can be applied to the conductivelayer.

FIGS. 57A-57D show examples that are similar to the examples of FIGS.55A-55D, and in which a bias signal can be applied to the conductivelayer.

FIG. 58 shows a switch assembly implemented in asingle-pole-single-throw (SPST) configuration utilizing an SOI FETdevice.

FIG. 59 shows that in some embodiments, the SOI FET device of FIG. 58can include a conductive layer feature as described herein.

FIG. 60 shows an example of how two SPST switches having one or morefeatures as described herein can be utilized to form a switch assemblyhaving a single-pole-double-throw (SPDT) configuration.

FIG. 61 shows that the switch assembly of FIG. 60 can be utilized in anantenna switch configuration.

FIG. 62 shows an example of how three SPST switches having one or morefeatures as described herein can be utilized to form a switch assemblyhaving a single-pole-triple-throw (SP3T) configuration.

FIG. 63 shows that the switch assembly of FIG. 62 can be utilized in anantenna switch configuration.

FIG. 64 shows an example of how four SPST switches having one or morefeatures as described herein can be utilized to form a switch assemblyhaving a double-pole-double-throw (DPDT) configuration.

FIG. 65 shows that the switch assembly of FIG. 64 can be utilized in anantenna switch configuration.

FIG. 66 shows an example of how nine SPST switches having one or morefeatures as described herein can be utilized to form a switch assemblyhaving a 3-pole-3-throw (3P3T) configuration.

FIG. 67 shows that the switch assembly of FIG. 66 can be utilized in anantenna switch configuration.

FIGS. 68A-68E show examples of how a DPDT switching configuration suchas the examples of FIGS. 64 and 65 can be operated to provide differentsignal routing functionalities.

FIGS. 69A and 69B show processes that can be implemented to form acavity in accordance with one or more embodiments disclosed herein.

FIGS. 70A and 70B show examples of various stages of a cavity formationprocess in accordance with one or more embodiments disclosed herein.

FIGS. 71A and 71B show die plan views associated with a cavity formationprocess in accordance with one or more embodiments.

FIGS. 72A and 72B show processes for forming a cavity in accordance withone or more embodiments disclosed herein.

FIGS. 73A-1 and 73B-1 show examples of various structures associatedwith a cavity formation processes in accordance with one or moreembodiments disclosed herein.

FIGS. 73A-2 and 73B-2 show examples of various structures associatedwith a cavity formation processes in accordance with one or moreembodiments disclosed herein.

FIGS. 74A and 74B show die plan views associated with a cavity formationprocess in accordance with one or more embodiments disclosed herein.

FIG. 75 shows a cavity formation process in accordance with one or moreembodiments disclosed herein.

FIGS. 76A and 76B show examples of various structures associated with acavity formation processes in accordance with one or more embodimentsdisclosed herein.

FIG. 77 shows a process for forming a cavity in accordance with one ormore embodiments disclosed herein.

FIG. 78 shows examples of various structures associated with a cavityformation processes in accordance with one or more embodiments disclosedherein.

FIG. 79 shows a process for forming a cavity in accordance with one ormore embodiments disclosed herein.

FIG. 80 shows examples of various structures associated with a cavityformation processes in accordance with one or more embodiments disclosedherein.

FIGS. 81A-81C show embodiments of die structures in accordance with oneor more embodiments.

FIGS. 82A-82C show embodiments of die structures in accordance with oneor more embodiments.

FIGS. 83A-83D depict non-limiting examples of switching circuits andbias/coupling circuits as described herein can be implemented on one ormore semiconductor die.

FIGS. 84A and 84B show plan and side views, respectively, of a packagedmodule having one or more features as described herein.

FIG. 85 shows a schematic diagram of an example switching configurationthat can be implemented in the module of FIGS. 70A and 70B.

FIG. 86 depicts an example wireless device having one or moreadvantageous features described herein.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

The headings provided herein, if any, are for convenience only and donot necessarily affect the scope or meaning of the claimed invention.

Introduction

Disclosed herein are various examples of a field-effect transistor (FET)device having one or more regions relative to an active FET portionconfigured to provide a desired operating condition for the active FET.In such various examples, terms such as FET device, active FET portion,and FET are sometimes used interchangeably, with each other, or somecombination thereof. Accordingly, such interchangeable usage of termsshould be understood in appropriate contexts.

FIG. 1 shows an example of a FET device 100 having an active FET 101implemented on a substrate 103. As described herein, such a substratecan include one or more layers configured to facilitate, for example,operating functionality of the active FET, processing functionality forfabrication and support of the active FET, etc. For example, if the FETdevice 100 is implemented as a silicon-on-Insulator (SOI) device, thesubstrate 103 can include an insulator layer such as a buried oxide(BOX) layer, an interface layer, and a handle wafer layer.

FIG. 1 further shows that in some embodiments, a region 105 below theactive FET 101 can be configured to include one or more features toprovide one or more desirable operating functionalities for the activeFET 101. For the purpose of description, it will be understood thatrelative positions above and below are in the example context of theactive FET 101 being oriented above the substrate 103 as shown.Accordingly, some or all of the region 105 can be implemented within thesubstrate 103. Further, it will be understood that the region 105 may ormay not overlap with the active FET 101 when viewed from above (e.g., ina plan view).

FIG. 2 shows an example of a FET device 100 having an active FET 101implemented on a substrate 103. As described herein, such a substratecan include one or more layers configured to facilitate, for example,operating functionality of the active FET 100, processing functionalityfor fabrication and support of the active FET 100, etc. For example, ifthe FET device 100 is implemented as a silicon-on-Insulator (SOI)device, the substrate 103 can include an insulator layer such as aburied oxide (BOX) layer, an interface layer, and a handle wafer layer.

In the example of FIG. 2, the FET device 100 is shown to further includean upper layer 107 implemented over the substrate 103. In someembodiments, such an upper layer can include, for example, a pluralityof layers of metal routing features and dielectric layers to facilitate,for example, connectivity functionality for the active FET 100.

FIG. 2 further shows that in some embodiments, a region 109 above theactive FET 101 can be configured to include one or more features toprovide one or more desirable operating functionalities for the activeFET 101. Accordingly, some or all of the region 109 can be implementedwithin the upper layer 107. Further, it will be understood that theregion 109 may or may not overlap with the active FET 101 when viewedfrom above (e.g., in a plan view).

FIG. 3 shows an example of a FET device 100 having an active FET 101implemented on a substrate 103, and also having an upper layer 107. Insome embodiments, the substrate 103 can include a region 105 similar tothe example of FIG. 1, and the upper layer 107 can include a region 109similar to the example of FIG. 2.

Examples related to some or all of the configurations of FIGS. 1-3 aredescribed herein in greater detail.

In the examples of FIGS. 1-3, the FET devices 100 are depicted as beingindividual units (e.g., as semiconductor die). FIGS. 4-6 show that insome embodiments, a plurality of FET devices having one or more featuresas described herein can be fabricated partially or fully in a waferformat, and then be singulated to provide such individual units.

For example, FIG. 4 shows an example FET device 100 implemented as anindividual SOI unit. Such an individual SOI device can include one ormore active FETs 101 implemented over an insulator such as a BOX layer104 which is itself implemented over a handle layer such as a silicon(Si) substrate handle wafer 106. In the example of FIG. 4, the BOX layer104 and the Si substrate handle wafer 106 can collectively form thesubstrate 103 of the examples of FIGS. 1-3, with or without thecorresponding region 105.

In the example of FIG. 4, the individual SOI device 100 is shown tofurther include an upper layer 107. In some embodiments, such an upperlayer can be the upper layer 103 of FIGS. 2 and 3, with or without thecorresponding region 109.

FIG. 5 shows that in some embodiments, a plurality of individual SOIdevices similar to the example SOI device 100 of FIG. 4 can beimplemented on a wafer 200. As shown, such a wafer can include a wafersubstrate 103 that includes a BOX layer 104 and a Si handle wafer layer106 as described in reference to FIG. 4. As described herein, one ormore active FETs can be implemented over such a wafer substrate.

In the example of FIG. 5, the SOI device 100 is shown without the upperlayer (107 in FIG. 4). It will be understood that such a layer can beformed over the wafer substrate 103, be part of a second wafer, or anycombination thereof.

FIG. 6A shows an example wafer assembly 204 having a first wafer 200 anda second wafer 202 positioned over the first wafer 200. FIG. 6B shows anunassembled view of the first and second wafers 200, 202 of the exampleof FIG. 6A.

In some embodiments, the first wafer 200 can be similar to the wafer 200of FIG. 5. Accordingly, the first wafer 200 can include a plurality ofSOI devices 100 such as the example of FIG. 4. In some embodiments, thesecond wafer 202 can be configured to provide, for example, a region(e.g., 109 in FIGS. 2 and 3) over a FET of each SOI device 100, and/orto provide temporary or permanent handling wafer functionality forprocess steps involving the first wafer 200.

Examples of SOI Implementation of FET Devices

Silicon-on-Insulator (SOI) process technology is utilized in manyradio-frequency (RF) circuits, including those involving highperformance, low loss, high linearity switches. In such RF switchingcircuits, performance advantage typically results from building atransistor in silicon, which sits on an insulator such as an insulatingburied oxide (BOX). The BOX typically sits on a handle wafer, typicallysilicon, but can be glass, borosilicon glass, fused quartz, sapphire,silicon carbide, or any other electrically-insulating material.

Typically, an SOI transistor is viewed as a 4-terminal field-effecttransistor (FET) device with gate, drain, source, and body terminals.However, an SOI FET can be represented as a 5-terminal device, with anaddition of a substrate node. Such a substrate node can be biased and/orbe coupled one or more other nodes of the transistor to, for example,improve both linearity and loss performance of the transistor. Variousexamples related to such a substrate node and biasing/coupling of thesubstrate node are described herein in greater detail.

In some embodiments, such a substrate node can be implemented with acontact layer having one or more features as described herein to allowthe contact layer to provide a desirable functionality for the SOI FET.Although various examples are described in the context of RF switches,it will be understood that one or more features of the presentdisclosure can also be implemented in other applications involving FETs.

FIG. 7 shows a terminal representation of an SOI FET 100 having nodesassociated with a gate, a source, a drain, a body, and a substrate. Itwill be understood that in some embodiments, the source and the draincan be reversed.

FIGS. 8A and 8B show side sectional and plan views of an example SOI FETdevice 100 having a node for its substrate. Such a substrate can be, forexample, a silicon substrate associated with a handle wafer 106 asdescribed herein. Although described in the context of such a handlewafer, it will be understood that the substrate does not necessarilyneed to have functionality associated with a handle wafer.

An insulator layer such as a BOX layer 104 is shown to be formed overthe handle wafer 106, and a FET structure is shown to be formed based onan active silicon device 102 over the BOX layer 104. In various examplesdescribed herein, and as shown in FIGS. 8A and 8B, the FET structure canbe configured as an NPN or PNP device.

In the example of FIGS. 8A and 8B, terminals for the gate, source, drainand body are shown to be configured and provided so as to allowoperation of the FET. A substrate terminal is shown to be electricallyconnected to the substrate (e.g., handle wafer) 106 through anelectrically conductive feature 108 extending through the BOX layer 104.Such an electrically conductive feature can include, for example, one ormore conductive vias, one or more conductive trenches, or anycombination thereof. Various examples of how such an electricallyconductive feature can be implemented are described herein in greaterdetail.

In some embodiments, a substrate connection can be connected to groundto, for example, avoid an electrically floating condition associatedwith the substrate. Such a substrate connection for grounding typicallyincludes a seal-ring implemented at an outermost perimeter of a givendie.

In some embodiments, a substrate connection such as the example of FIGS.8A and 8B can be utilized to bias the substrate 106, to couple thesubstrate with one or more nodes of the corresponding FET (e.g., toprovide RF feedback), or any combination thereof. Such use of thesubstrate connection can be configured to, for example, improve RFperformance and/or reduce cost by eliminating or reducing expensivehandle-wafer treatment processes and layers. Such performanceimprovements can include, for example, improvements in linearity, lossand/or capacitance performance.

In some embodiments, the foregoing biasing of the substrate node can be,for example, selectively applied to achieve desired RF effects only whenneeded or desired. For example, bias points for the substrate node canbe connected to envelope-tracking (ET) bias for power amplifier (PA) toachieve distortion cancelation effects.

In some embodiments, a substrate connection for providing the foregoingexample functionalities can be implemented as a seal-ring configurationsimilar to the grounding configuration, or other connectionconfigurations. Examples of such substrate connections are describedherein in greater detail.

FIG. 9 shows a side sectional view of an SOI substrate 10 that can beutilized to form an SOI FET device 100 of FIG. 10 having an electricalconnection for a substrate layer 106 (e.g., Si handle layer). In FIG. 9,an insulator layer such as a BOX layer 104 is shown to be formed overthe Si handle layer 106. An active Si layer 12 is shown to be formedover the BOX layer 104. It will be understood that in some embodiments,the foregoing SOI substrate 10 of FIG. 9 can be implemented in a waferformat, and SOI FET devices having one or more features as describedherein can be formed based on such a wafer.

In FIG. 10, an active Si device 102 is shown to be formed from theactive Si layer 12 of FIG. 9. One or more electrically conductivefeatures 108 such as vias are shown to be implemented through the BOXlayer 104, relative to the active Si device 102. In some embodiments,such conductive features (108) can allow the Si handle layer 106 to becoupled to the active Si device (e.g., a FET), be biased, or anycombination thereof. Such coupling and/or biasing can be facilitated by,for example, a metal stack 110. In some embodiments, such a metal stackcan allow the conductive features 108 to be electrically connected to aterminal 112. In the example of FIG. 10, one or more passivation layers,one or more dielectric layers, or some combination thereof (collectivelyindicated as 114) can be formed to cover some or all of such a metalstack.

In some embodiments, a trap-rich layer 14 can be implemented between theBOX layer 104 and the Si handle layer 106. However, and as describedherein, the electrical connection to the Si handle layer 106 through theconductive feature(s) 108 can eliminate or reduce the need for such atrap-rich layer which is typically present to control charge at aninterface between the BOX layer 104 and the Si handle layer 106, andwhich can involve costly process steps.

Aside from the foregoing example of eliminating or reducing the need fora trap-rich layer, the electrical connection to the Si handle layer 106can provide a number of advantageous features. For example, theconductive feature(s) 108 can allow forcing of excess charge at theBOX/Si handle interface to thereby reduce unwanted harmonics. In anotherexample, excess charge can be removed through the conductive feature(s)108 to thereby reduce the off-capacitance (Coff) of the SOI FET. In yetanother example, the presence of the conductive feature(s) 108 can lowerthe threshold of the SOI FET to thereby reduce the on-resistance (Ron)of the SOI FET.

FIG. 11 shows an example FET device 100 that is similar to the exampleof FIG. 10, but in which a trap-rich layer (14 in FIG. 10) issubstantially absent. Accordingly, in some embodiments, the BOX layer104 and the Si handle layer 106 can be in substantially directengagement with each other.

In the example of FIG. 11, the conductive features (e.g., vias) 108 aredepicted as extending through the BOX layer 104 and contacting the Sihandle layer 106 generally at the BOX/Si handle interface. It will beunderstood that in some embodiments, such conductive features can extenddeeper into the Si handle layer 106.

In the examples of FIGS. 10 and 11, the conductive features 108 aredepicted as being coupled to other electrical connections associatedwith the active Si device 102. FIG. 12 shows that in some embodiments,an electrical connection to a substrate (e.g., Si handle layer 106) canbe implemented without being coupled to such other electricalconnections associated with the active Si device 102. For example, aconductive feature 108 such as a via is shown to extend through the BOXlayer 104 so as to form a contact with the Si handle layer 106. Theupper portion of the through-BOX conductive feature 108 is shown to beelectrically connected to a terminal 113 that is separate from aterminal 112.

In some embodiments, the electrical connection between the separateterminal 113 and the Si handle layer 106 (through the conductive feature108) can be configured to allow, for example, separate biasing of aregion in the substrate (e.g., Si handle layer 106) to achieve a desiredoperating functionality for the active Si device 102. Such an electricalconnection between the separate terminal 113 and the Si handle layer 106is an example of a non-grounding configuration utilizing one or morethrough-BOX conductive features 108.

In the examples of FIGS. 10-12, the through-BOX conductive features(108) are depicted as either being coupled to electrical connectionsassociated with the active Si device 102, or as being separate from suchelectrical connections. It will be understood that other configurationscan also be implemented. For example, one or more through-BOX conductivefeatures (108) can be coupled to one node of the active Si device 102(e.g., source, drain or gate), but not other node(s). Non-limitingexamples of circuit representations of such coupling (or non-coupling)between the substrate node and other nodes of the active Si device aredisclosed herein in greater detail.

In the example of FIG. 10, the trap-rich layer 14 can be implemented asan interface layer between the BOX layer 104 and the Si handle layer106, to provide one or more functionalities as described herein. In theexamples of FIGS. 11 and 12, such a trap-rich interface layer 14 can beomitted as described herein.

FIG. 13 shows that in some embodiments, a handle wafer 106 (e.g., Sihandle layer) can include a plurality of doped regions 117 implementedto provide one or more functionalities similar to a trap-rich interfacelayer (e.g., 14 in FIG. 10). Such doped regions can be, for example,generally amorphous and have relatively high resistivity when comparedto other portions of the handle wafer 106. In some embodiments, suchdoped regions can include crystalline structure, amorphous structure, orany combination thereof.

In the example of FIG. 13, two FETs 102 and islands 115 are shown to beformed from an active Si layer 12 which is implemented over a BOX layer104. The BOX layer is shown to be implemented over the handle wafer 106having the doped regions 117. In some embodiments, such doped regions(117) can be implemented to be laterally positioned generally under gapsbetween the FETs 102 and/or the islands 115.

FIG. 13 further shows that in some embodiments, the handle wafer 106having doped regions such as the foregoing doped regions 117 can bebiased as described herein through one or more conductive features 108such as vias. As described herein, such conductive features 108 can becoupled to other portions of FET(s), to a separate terminal, or anycombination thereof, so as to provide biasing to the handle wafersubstrate 106 to achieve one or more desired operating functionalitiesfor the FET(s).

In the example of FIG. 13, a given conductive feature 108 can interactwith a FET 102 through the handle wafer 106. For example, the BOX layerbeing interposed between the FET 102 and the handle wafer 106 can resultin a capacitance C therebetween. Further, a resistance R can existbetween the end of the conductive feature 108 and the BOX/handle waferinterface. Accordingly, a series RC coupling can be provided between theconductive feature 108 and the underside of the FET 102. Thus, providinga bias signal to handle wafer 106 through the conductive feature 108 canprovide a desirable operating environment for the FET 102.

In the example of FIG. 13, a given conductive feature 108 is depicted asbeing laterally separated from the nearest FET 102 so as to include atleast one doped region 117 in the handle wafer 106. Accordingly, theresulting resistive path (with resistance R) can be relatively long.Thus, the resistance R can be a high resistance.

Referring to the examples of FIGS. 10-13, it is noted that in someembodiments, a given conductive feature 108 can be implemented so as tobe laterally separated from the nearest FET 102 by a separationdistance. Such a separation distance can be, for example, at least 1 μm,2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm. In someembodiments, the separation distance can be in a range of 5 μm to 10 μm.For the purpose of description, it will be understood that such aseparation distance can be, for example, a distance between the closestportions of the conductive feature 108 and the corresponding FET 102 inthe active Si layer (12).

Described herein are, among others, examples related to SOI FET deviceshaving a contact layer. FIGS. 14A and 14B show side sectional and planviews of an example SOI FET 100 having such a contact layer (260), inthe context of the example SOI FET 100 of FIGS. 8A and 8B. Examples ofhow such a contact layer can be formed, as well as how such a contactlayer can be configured in different manners, are described herein ingreater detail.

In some embodiments, a contact layer having one or more features asdescribed herein can be implemented on a side of a BOX layer oppositefrom the side on which a FET is formed. In the context of the FET beingformed on the front or upper side of such a BOX layer, the contact layercan be implemented on the back or lower side of the BOX. Accordingly,relational terms “back,” “backside,” “lower,” “lower side,” etc.referring to position of a contact layer will be understood in theforegoing context.

It will also be understood that a contact layer having one or morefeatures as described herein can also be referred to as a conductivecontact layer, a substrate contact layer, a conductive layer, or somecombination thereof. In some embodiments, such a contact layer can beimplemented to be between a BOX layer and a substrate contact layer. Insome embodiments, such a contact layer can be implemented on thebackside of a BOX layer without a substrate layer. Accordingly, it willbe understood that the foregoing examples of interchangeable terms forthe contact layer (including the substrate contact layer) can refer toimplementations with or without a substrate layer.

In the example of FIG. 14, the contact layer 260 is depicted as being inelectrical contact with the conductive feature 108. Such a conductivefeature (108) can allow the contact layer 260 to be in electricalcontact with, for example, a substrate node. As described herein, such asubstrate node can be electrically connected to a bias circuit and/or becoupled to one or more portions of the FET. Although various examplesare described herein in the context of the contact layer 260 beingelectrically connected through one or more through-BOX conductivefeature (such as the conductive feature 108 of FIG. 14), it will beunderstood that a contact layer (such as the contact layer 260 of FIG.14) can be electrically connected in other configurations so as toprovide an electrical connection to a bias circuit and/or one or moreportions of a corresponding FET.

FIG. 15 shows that in some embodiments, a contact layer 260 having oneor more features as described herein can be implemented in an FET device100 that is similar to the example of FIG. 11 (e.g., in which atrap-rich layer (14 in FIG. 10) is substantially absent). Accordingly,in some embodiments, the contact layer 260 can be in substantiallydirect contact with the BOX layer 104 on one side, and in substantiallydirect contact with the Si handle layer 106 on the other side.

In the example of FIG. 15, the conductive features (e.g., vias) 108 aredepicted as extending through the BOX layer 104 and contacting thecontact layer 260. As described herein, such conductive features can becoupled to other electrical connections associated with the active Sidevice 102.

FIG. 16 shows that in some embodiments, an electrical connection to acontact layer 260 can be implemented without being coupled to such otherelectrical connections associated with the active Si device 102. Forexample, a conductive feature 108 (such as a via) is shown to extendthrough the BOX layer 104 so as to form a contact with the contact layer260. The upper portion of the through-BOX conductive feature 108 isshown to be electrically connected to a terminal 113 that is separatefrom a terminal 112.

In some embodiments, the electrical connection between the separateterminal 113 and the contact layer 260 (through the conductive feature108) can be configured to allow, for example, separate biasing orcontrolling of a region underneath the active Si device 102 to achieve adesired operating functionality for the active Si device 102. Examplesrelated to such operating functionality are described herein in greaterdetail.

In the examples of FIGS. 15 and 16, the through-BOX conductive features(108) are depicted as either being coupled to electrical connectionsassociated with the active Si device 102, or as being separate from suchelectrical connections. It will be understood that other configurationscan also be implemented. For example, one or more through-BOX conductivefeatures (108) can be coupled to one node of the active Si device 102(e.g., source, drain or gate), but not other node(s). Non-limitingexamples of circuit representations of such coupling (or non-coupling)between a node associated with the contact layer 260 and other nodes ofthe active Si device are disclosed herein in greater detail.

FIG. 17 shows that in some embodiments, a contact layer 260 having oneor more features as described herein can be implemented in an FET device100 that is similar to the example of FIG. 10 (e.g., in which atrap-rich layer 14 is present). In the example of FIG. 17, the contactlayer 260 can be implemented to be between the trap-rich layer 14 andthe BOX layer 104.

In the example of FIG. 17, the contact layer 260 is shown to be coupledto one or more portions of the active Si device 102 (e.g., through oneor more through-BOX conductive features 108). It will be understood thatin some embodiments, the contact layer of FIG. 17 can be coupled to aseparate terminal such as the separate terminal 113 of FIG. 16.

FIGS. 18 and 19 show that in some embodiments, a contact layer 260having one or more features as described herein can be implemented in anFET device 100 that is similar to the example of FIG. 13 (e.g., in whicha plurality of doped regions 117 are present). In the example of FIG.18, the contact layer 260 can be implemented to be substantially betweenthe plurality of doped regions 117 and the BOX layer 104. In the exampleof FIG. 19, the contact layer 260 can be configured to allow theplurality of doped regions 117 to be substantially in contact with theBOX layer 104. In some embodiments, such a configuration can be achievedby, for example, the contact layer 260 having a plurality of openings toallow the corresponding doped regions 117 to be in contact with the BOXlayer 104. An example of such a perforated configuration of the contactlayer 260 is described herein in greater detail.

In the examples of FIGS. 18 and 19, the contact layer 260 can be coupledto one or more portions of an active device 102, be coupled to aseparate terminal, or be configured in some combination thereof, similarto the examples of FIGS. 15 and 16.

Examples Related to Fabrication of SOI FET Devices

FIGS. 20 and 22 show processes 130 and 200 that can be implemented tofabricate an SOI device having one or more features as described herein.FIGS. 21 and 23 show examples of various stages of the fabricationprocesses of FIGS. 20 and 22. In some embodiments, some or all of thevarious process steps can be implemented utilizing wafer processingtechnologies.

In some embodiments, fabrication of an SOI device having one or morefeatures as described herein can include fabrication of a wafer havingan electrical connection formed between a contact layer and a terminal.An example of a wafer that can be utilized to achieve such a connectionbetween the contact layer and the terminal is shown in FIG. 21 as 146,and examples of process steps in FIG. 20 can be implemented to achievesuch a wafer configuration.

In block 132 of FIG. 20, an SOI substrate can be formed or provided. Instate 140 of FIG. 21, such an SOI substrate can include an Si substrate106 such as an Si handle wafer, an oxide layer 104 over the Si substrate106, and an active Si layer 12 over the oxide layer 104. Such an SOIsubstrate may or may not have a trap-rich layer (e.g., 14 in FIGS. 9 and10) between the oxide layer 104 and the Si substrate 106. Similarly,such an SOI substrate may or may not have doped regions (e.g., 117 inFIG. 13) in the Si substrate 106.

In block 134 of FIG. 20, one or more FETs can be formed with the activeSi layer. In state 142 of FIG. 21, such a FET is depicted as 150.

In block 136 of FIG. 20, one or more conductive features such as viascan be formed through the oxide layer, to the Si substrate, and relativeto the FET(s). In state 144 of FIG. 21, such a conductive via isdepicted as 108. As described herein, such an electrical connectionthrough the oxide layer 104 to the Si substrate 106 can also beimplemented utilizing other conductive features such as one or moreconductive trenches.

In the example of FIGS. 20 and 21, it will be understood that blocks 134and 136 may or may not be performed in the example sequence shown. Insome embodiments, conductive feature(s) such as a deep trench can beformed and filled with poly prior to the formation of the FET(s). Insome embodiments, such conductive feature(s) can be formed (e.g., cutand filled with a metal such as tungsten (W) after the formation of theFET(s). It will be understood that other variations in sequencesassociated with the example of FIGS. 20 and 21 can also be implemented.

In block 138 of FIG. 20, electrical connections can be formed for theconductive vias and the FET(s). In state 146 of FIG. 21, such electricalconnections are depicted as a metallization stack collectively indicatedas 110. Such a metal stack can electrically connect the FET(s) 150 andthe conductive vias 108 to one or more terminals 112. In the examplestate 146 of FIG. 21, a passivation layer 114 is shown to be formed tocover some or all of the metallization stack 110.

Referring to FIGS. 22 and 23, process 200 can be a continuation of theprocess 130 associated with FIGS. 20 and 21 (e.g., both processesimplemented at one fabrication facility), a separate process thatutilizes as an input a wafer (e.g., configuration 146 in FIG. 21)resulting from the process 130 (e.g., two processes implemented atdifferent fabrication facilities), or any combination thereof.Accordingly, in block 202 of the process 200 of FIG. 22A, an SOI waferhaving an electrical connection for a substrate layer can be formed orprovided. In FIG. 23A, state 146 can be similar to state 146 of FIG. 21.

In block 204 of FIG. 22A, a carrier layer can be formed or attached onthe front side of the SOI wafer. For the purpose of description, thefront side of the SOI wafer can include the side opposite from thesubstrate layer. In state 250 of FIG. 23A, such a carrier layer isdepicted as 252. As described herein, such a carrier layer on the frontside of the SOI wafer can allow fabrication steps to be performed on theback side to facilitate formation of a contact layer.

In some embodiments, the carrier layer can be a temporarily attachedlayer, or a permanently attached layer. In some embodiments, the carrierlayer can be any material suitable for being attached (temporarily orpermanently) to one side of a wafer so as to allow one or more processsteps to be performed on the other side of the wafer. Such a carrierlayer can include, for example, another wafer, silicon, glass, quartz,silicon carbide, sapphire, etc. Such a carrier layer can be attached tothe front side of the SOI wafer utilizing, for example, a spun-onadhesive.

In block 206 of FIG. 22A, some or all of the substrate layer can beremoved from the back side of the SOI wafer. In FIG. 23A, such asubstrate layer is depicted as 106 in state 250. In state 254, such asubstrate layer is shown to be removed so as to expose a surface 256.

In some embodiments, the substrate layer can be removed sufficiently toexpose the conductive feature(s) 108 such as conductive via(s). In someembodiments, such removal of the substrate layer may or may not exposethe oxide layer 104. Such removal of the substrate layer can be achievedby, for example, grinding, chemical mechanical polishing (CMP),selective etching using an appropriate chemistry, or some combinationthereof.

In block 208 of FIG. 22A, a contact layer can be formed on the surfaceresulting from the removal of the substrate layer. In state 258 of FIG.23A, such a contact layer is depicted as 260 formed on the exposedsurface 256.

As described herein, such a contact layer can be formed so as to be inelectrical contact with the conductive feature(s) 108. In someembodiments, the contact layer 260 can include one or more layers thatcan be, for example, patterned, deposited, implanted, and/or formed bysurface treatment on the exposed surface 256 of the oxide layer 104.Such a contact layer on the oxide layer 104 can have, for example,conductive, resistive, dielectric, inductive, rectifying,semi-insulating, semiconducting, trap and/or hole type properties.

In block 210 of FIG. 22B, an interface layer can be formed over thecontact layer. In state 262 of FIG. 23B, such an interface layer isdepicted as 264 formed so as to substantially cover the contact layer260 and the surface 256. In some embodiments, such an interface layer(264) can be configured to facilitate attachment of a replacementsubstrate layer.

In block 212 of FIG. 22B, a replacement substrate layer can be formed onor attached to the interface layer. In state 266 of FIG. 23B, such areplacement substrate layer is depicted as 268.

In some embodiments, the substrate layer 268 can be a wafer, and such awafer can be wafer-bonded to the oxide layer 104 of the SOI wafer, withor without the interface layer 104. Such wafer-bonding can be achievedby one or more wafer-bonding techniques. In some embodiments, thereplacement substrate wafer can include, for example, silicon, glass,quartz, sapphire, silicon carbide, and/or gallium arsenide. Othermaterials can also be utilized for the replacement substrate wafer.

In block 214 of FIG. 22B, the carrier layer can be removed from the SOIwafer's front side. In state 270 of FIG. 23B, the front side of the SOIwafer is shown to have the carrier layer removed so as to substantiallyexpose the terminals 112. Such removal of the carrier layer from thefront side of the SOI wafer can be facilitated by the replacementsubstrate layer 268 now providing, among others, handle layerfunctionality.

In the example state 270 of FIG. 23B, it is assumed that the carrierlayer about the terminal 112 was a temporary layer. Such a temporarylayer can be removed substantially completely from the front side of theSOI wafer. In some embodiments, at least some of the carrier layer canremain on the front side of the SOI wafer. In some embodiments, thefront side of the SOI wafer can be further processed.

In the fabrication example described in reference to FIGS. 22 and 23,layer transfer techniques are utilized. However, it will be understoodthat use of other process techniques can be utilized to form a contactlayer on or near the back side surface of an oxide layer of an SOIdevice.

In some embodiments, a contact layer as described herein can be utilizedto, for example, provide bias for the substrate of an SOI device. Insome embodiments, a contact layer as described herein can also beutilized for other applications. For example, FIG. 24 shows that acontact layer 260 can be configured to be utilized as a back-gate to atransistor. Such a back-gate can provide one or more functionalitiessuch as assisting in depleting or increasing charge in the activechannel of an SOI FET 100. In some embodiments, the contact layer 260can be dimensioned appropriately (e.g., depicted as dimension 280) toprovide such back-gate functionality.

In some embodiments, the contact layer 260 can be separated from theactive channel of an SOI FET 100 by a desired distance 282 to provide adesired functionality such as the back-gate functionality. In someembodiments, such a separation distance (282) can be achieved by, forexample, a selected thickness of the BOX layer 104. In some embodiments,both of the dimension 280 and the separation distance 282 can beselected appropriately to achieve one or more functionalities for theFET.

FIGS. 25A and 25B show additional examples of how a contact layer 260having one or more features as described herein can be dimensioned toprovide one or more desirable functionalities. In the example of FIG.25A, the contact layer 260 is depicted as having a rectangular footprintshape dimensioned to be in electrical contact with a conductive feature108, and to provide at least some overlap with a gate region associatedwith a FET 102.

FIG. 25B shows that in some embodiments, a footprint shape of a contactlayer can be selected to facilitate one or more functionalities. Forexample, suppose that an additional overlap is desired between asubstrate contact layer and a gate region of the FET 102 (e.g., comparedto the example of FIG. 25A). To achieve such an increased overlap, acontact layer 260 can include an extended area 290 (e.g., depicted asadditional areas above and below the original rectangular shape of thecontact layer 260) to accommodate such an additional overlap.

In some embodiments, other design parameters associated with a contactlayer can be implemented to achieve one or more desired functionalities.For example, design parameters such as contact layer material(s),thickness of the oxide layer, and/or the biasing networks can beconfigured appropriately for devices such as MOSFET devices to lowerresistance, improve linearity performance, lower threshold voltage,increase breakdown voltage, and/or improve isolation performance of thetransistor.

In the various examples described in reference to FIGS. 14, 24 and 25,the contact layer 260 is depicted as being located generally under acircuit element such as a FET. However, it will be understood that acontact layer having one or more features as described herein can alsobe implemented in other configurations. For example, different patternsof electrical connections can be implemented for substrates. In someembodiments, contact layers can be configured to facilitate suchpatterns of electrical connections for substrates; and such patterns mayor may not be under circuit elements.

FIGS. 26A-26F show non-limiting examples of how contact layers havingone or more features as described herein can be implemented relative tocircuit elements. In each of the examples, a contact layer 260 is shownto be electrically connected through one or more conductive vias 108;however, it will be understood that such electrical connections can alsobe implemented by other conductive features such as trenches.

FIG. 26A shows an example where a contact layer 260 can be locatedgenerally below a circuit element 300. Such a configuration canrepresent, for example, the examples described herein in reference toFIGS. 14, 24 and 25.

FIG. 26B shows an example where a contact layer 260 can be a strip thatforms a perimeter around a circuit element 300. In some embodiments,such a configuration can be implemented with, for example, an examplepattern of conductive vias that generally surround the circuit element300.

FIGS. 26C and 26D show examples where contact layers 260 can be stripsthat form partial perimeters about their respective circuit elements300. For example, FIG. 26C shows a U-shape configuration, and FIG. 26Dshows an L-shaped configuration. In some embodiments, suchconfigurations can be implemented with, for example, example patterns ofconductive vias that partially surround the circuit element 300.

FIG. 26E shows an example where a contact layer 260 can be a strip thatforms a segment at or near a side of a circuit element 300. In someembodiments, such a configuration can be implemented with, for example,an example pattern of conductive vias that form a segment at or near aside of the circuit element 300.

FIG. 26F shows an example where a contact layer 260 can have arelatively small pad shape that is not necessarily a strip. Such aconfiguration can be utilized in applications where relatively discretecontact layer is desired. In some embodiments, such a configuration canbe implemented with, for example, an example pattern of one or moreconductive vias grouped in a discrete manner.

It will be understood that contact layers having one or more features asdescribed herein can also be configured in other ways. For example,there may be more than one contact layers for a given circuit element.

FIG. 27 shows that in some embodiments, a contact layer 260 can includeone or more openings. Such a configuration can, for example, accommodatefeatures or regions formed on a handle wafer layer (e.g., Si handlewafer). For example, and in the context of the example configuration ofFIG. 19 (in which a plurality of doped regions 117 are provided on thehandle wafer 106, the contact layer 260 of FIG. 19 can include aplurality of openings as shown in FIG. 27 to accommodate such dopedregions.

In the example of FIG. 27, such openings in the contact layer 260 areshown to substantially expose the corresponding doped regions. In someembodiments, such openings can also be dimensioned to partially exposecorresponding doped regions.

In the example of FIG. 27, the contact layer 260 can be electricallyconnected to one or more portions of an FET and/or a terminal through,for example, one or more conductive vias 108. It will be understood thatother numbers and/or other arrangements of conductive vias can beimplemented.

Examples Related to Biasing and/or Coupling of SOI FET Devices

FIG. 28 shows that in some embodiments, an SOI FET device 100 having oneor more features as described herein can have its contact layer biasedby, for example, a substrate bias network 152. Various examples relatedto such a substrate bias network are described herein in greater detail.

In the example of FIG. 28, other nodes such as the gate and the body ofthe SOI FET device 100 can also be biased by their respective networks.Among others, examples related to such gate and body bias networks canbe found in PCT Publication No. WO 2014/011510 entitled CIRCUITS,DEVICES, METHODS AND COMBINATIONS RELATED TO SILICON-ON-INSULATOR BASEDRADIO-FREQUENCY SWITCHES, the disclosure of which is hereby expresslyincorporated by reference herein in its entirety.

FIGS. 29-31 show that in some embodiments, SOI FETs having one or morefeatures as described herein can be implemented in RF switchingapplications.

FIG. 29 shows an example of an RF switching configuration 160 having anRF core 162 and an energy management (EM) core 164. Additional detailsconcerning such RF and EM cores can be found in the above-referenced PCTPublication No. WO 2014/011510. The example RF core 162 of FIG. 29 isshown as a single-pole-double-throw (SPDT) configuration in which seriesarms of transistors 100 a, 100 b are arranged between a pole and firstand second throws, respectively.

Nodes associated with the first and second throws are shown to becoupled to ground through their respective shunt arms of transistors 100c, 100 d.

In the example of FIG. 29, some or all of the transistors 100 a-100 dcan include contact layers as described herein. Such contact layers canbe utilized to provide desirable functionalities for the correspondingtransistors.

FIG. 30 shows an example of the RF core 162 of FIG. 29, in which each ofthe switch arms 100 a-100 d includes a stack of FET devices. For thepurpose of description, each FET in such a stack can be referred to as aFET, the stack itself can be collectively referred to as a FET, or somecombination thereof can also be referred to as a FET. In the example ofFIG. 30, each FET in the corresponding stack one or more contact layersas described herein. It will be understood that some or all of the FETdevices in the RF core 162 can include such contact layers.

FIG. 31 shows an example of the biasing configuration 150 of FIG. 28,implemented in a switch arm having a stack of FETs 100 as described inreference to FIG. 30. In the example of FIG. 31, each FET in the stackcan be biased with a separate substrate bias network 152, the FETs inthe stack can be biased with a plurality of substrate bias networks 152,all of the FETs in the stack can be biased with a common substrate biasnetwork, or any combination thereof. Such possible variations can alsoapply to gate biasing (156) and body biasing (154).

FIG. 32 shows that a pattern 261 of one or more contact layers 260 canbe implemented to be electrically connected as described herein. In someembodiments, such a pattern of contact layers can also be electricallyconnected (depicted as 172) to, for example, a substrate bias network152. In some embodiments, and as described herein, such a pattern ofcontact layers can be electrically connected to another node of the SOIFET device, with or without the substrate bias network 152. In someembodiments, some or all of the foregoing electrical connections for thecontact layer(s) can be facilitated by corresponding patterns ofconductive features configured to provide substrate biasingfunctionality.

FIGS. 33-38 show non-limiting examples of the pattern 261 of one or morecontact layers of FIG. 32. In the examples of FIGS. 33-37, a pattern ofsuch contact layer(s) (indicated as 170) is depicted as generallysurrounding a corresponding circuit element. However, and as shown inFIGS. 38A-38E, such a pattern of contact layer(s) (indicated as 261) mayor may not surround a corresponding circuit element.

In the examples of FIGS. 33-38, it will be understood that for some orall of such examples, the pattern of contact layer(s) can beelectrically connected to another node of the SOI FET device, with orwithout the substrate bias network 152.

FIG. 33 shows an example configuration 160 in which a pattern 170 ofcontact layers as described herein can generally form a ring shapedperimeter substantially around an entire die having an RF core 162 andan EM core 164. Accordingly, the RF core 162 and the EM core 164collectively can be a circuit element associated with the pattern 170 ofcontact layers.

FIG. 34 shows an example configuration 160 in which a pattern of contactlayers as described herein can generally form a ring shaped distributionimplemented substantially around each of an RF core 162 (pattern 170 a)and an EM core 164 (pattern 170 b) of a switching die. Accordingly, theRF core 162 can be a circuit element associated with the pattern 170 aof contact layers, and the EM core 164 can be a circuit elementassociated with the pattern 170 b of contact layers. Although both ofthe RF and EM cores are depicted as having respective patterns ofcontact layers, it will be understood that one pattern can have suchcontact layers while the other pattern does not. For example, the RFcore can have such a pattern of contact layers while the EM core doesnot.

FIGS. 35-37 show examples of one or more patterns of contact layers asdescribed herein that can be implemented for an RF core 162. FIG. 35shows an example configuration in which a pattern 170 of contact layersas described herein can generally form a ring shaped distributionimplemented substantially around an assembly of series arms 100 a, 100 band shunt arms 100 c, 100 d. Accordingly, the RF core 162 can be acircuit element associated with the pattern 170 of contact layers.

FIG. 36 shows an example configuration in which a pattern of contactlayers as described herein can generally form a ring shaped distributionimplemented substantially around each of series arms 100 a (pattern 170a), 100 b (pattern 170 b) and shunt arms 100 c (pattern 170 c), 100 d(pattern 170 d). Accordingly, each arm (100 a, 100 b, 100 c or 100 d)can be a circuit element associated with the corresponding pattern (170a, 170 b, 170 c or 170 d) of contact layers.

FIG. 37 shows an example configuration in which a pattern 170 of contactlayers as described herein can generally form a ring shaped distributionimplemented substantially around each FET in a given arm. Accordingly,each FET can be a circuit element associated with the correspondingpattern of contact layers.

In the examples of FIGS. 35-37, each component at different levels ofthe RF core is shown to be provided with a pattern of contact layers.For example, each arm in FIG. 36 is shown to include a pattern ofcontact layers, and each FET in FIG. 37 is shown to include a pattern ofcontact layers. It will be understood that not every one of suchcomponents necessarily needs to have such pattern of contact layers.Further, it will be understood that various combinations of the patternsof contact layers associated with different levels of the RF core can becombined. For example, an RF core can include a pattern of contactlayers around the RF core itself, and one or more additional patterns ofcontact layers can also be implemented for selected arm(s) and/orFET(s).

As described herein, a pattern of contact layers can be implementedaround a circuit element, partially around a circuit element, as asingle feature, or any combination thereof.

FIGS. 38A-38E show non-limiting examples of such patterns. In suchexamples, the patterns are depicted as being electrically connected totheir respective substrate bias networks. However, and as describedherein, such patterns can be electrically connected to other part(s) of,for example, corresponding FET with or without such substrate biasnetworks.

FIG. 38A shows an example in which a pattern 261 of one or more contactlayers as described herein can be implemented around a circuit element,similar to the examples of FIGS. 33-37. Such a pattern can beelectrically connected to a substrate bias network and/or anotherportion of the circuit element.

FIG. 38B shows an example in which a pattern 261 of contact layers asdescribed herein can be implemented partially around a circuit element.In the particular example of FIG. 38B, such a partially surroundingpattern can be a U-shaped pattern in which one or more contact layersare implemented on three sides, but not on the fourth side relative tothe circuit element. Such a pattern can be electrically connected to asubstrate bias network and/or another portion of the circuit element.

FIG. 38C shows another example in which a pattern 261 of contact layersas described herein can be implemented partially around a circuitelement. In the particular example of FIG. 38C, such a partiallysurrounding pattern can be an L-shaped pattern in which one or morecontact layers are implemented on two adjacent sides, but not on theother two sides relative to the circuit element. Such a pattern can beelectrically connected to a substrate bias network and/or anotherportion of the circuit element. In some embodiments, two sides havingpatterns of contact layers can be opposing sides.

FIG. 38D shows yet another example in which a pattern 261 of contactlayers as described herein can be implemented partially around a circuitelement. In the particular example of FIG. 38D, such a partiallysurrounding pattern can be a pattern in which one or more contact layersare implemented on one side, but not on the remaining three sidesrelative to the circuit element. Such a pattern can be electricallyconnected to a substrate bias network and/or another portion of thecircuit element.

FIG. 38E shows an example in which a pattern 261 of contact layers asdescribed herein can be implemented as one or more discrete contactareas. In the particular example of FIG. 38E, such a pattern can be apattern in which a single contact layer is implemented relative to thecircuit element. Such a pattern can be electrically connected to asubstrate bias network and/or another portion of the circuit element.

In the examples of FIGS. 38A-38E, a given pattern 261 can include one ormore discrete and/or contiguous contact layers. For the purpose ofdescription, it will be understood that a contiguous pattern (e.g., twojoined segments in the example of FIG. 38C) can include contact layersthat are electrically connected to a common substrate bias networkand/or another common portion of the circuit element.

FIGS. 39A and 39B show that in some embodiments, there may be more thanone pattern of contact layers implemented relative a circuit element.Such patterns of contact layers can be electrically connected toseparate substrate bias networks and/or portions of the circuit element,be electrically connected to a common substrate bias network and/oranother common portion of the circuit element, or any combinationthereof.

For example, FIG. 39A shows a configuration in which two opposing sidesrelative to a circuit element are provided with first and secondpatterns 261 of contact layers. The first pattern can be electricallyconnected to a first substrate bias network 152 a and/or a first portionof the circuit element, and the second pattern can be electricallyconnected to a second substrate bias network 152 b and/or a secondportion of the circuit element.

In another example, 39B shows a configuration in which two opposingsides relative to a circuit element are provided with first and secondpatterns 261 of contact layers, similar to the example of FIG. 39A. Bothof the first and second patterns 261 can be electrically connected to acommon substrate bias network 152 and/or a common portion of the circuitelement.

FIGS. 40-57 show non-limiting examples of substrate bias networks and/orother portions of an SOI FET device 100 that can be coupled with acontact layer of the SOI FET device 100. Such coupling with the contactlayer can be facilitated by one or more patterns of conductive featuresas described herein. In some embodiments, such contact layers canprovide one or more functionalities for the SOI FET device 100,including, for example, substrate biasing functionality, back-gatefunctionality, or some combination thereof.

FIG. 40 shows an example in which a contact layer of an SOI FET device100 can be electrically connected to a substrate bias network 152. Sucha substrate bias network can be configured to allow application of a DCcontrol voltage (V_control) to the contact layer.

FIG. 41 shows an example in which a contact layer of an SOI FET device100 can be electrically connected to a substrate bias network 152. Sucha substrate bias network can be configured to allow application of a DCcontrol voltage (V_control) to the contact through a resistance R (e.g.,a resistor).

FIG. 42 shows an example in which a contact layer of an SOI FET device100 can be electrically connected to a gate node (e.g., back-side of thegate) of the SOI FET device 100. In some embodiments, such a couplingmay or may not include a resistance R (e.g., a resistor). In someembodiments, such a coupling may or may not be part of a substrate biasnetwork 152 (if any).

FIG. 43 shows an example in which a contact layer of an SOI FET device100 can be electrically connected to a gate node of the SOI FET device100 through a phase-shift circuit. In the example shown, the phase-shiftcircuit includes a capacitance (e.g., a capacitor); however, it will beunderstood that the phase-shift circuit can be configured in othermanners. In some embodiments, such a coupling may or may not include aresistance R (e.g., a resistor). In some embodiments, such a couplingmay or may not be part of a substrate bias network 152 (if any).

FIG. 44 shows an example in which a contact layer of an SOI FET device100 can be electrically connected to a gate node of the SOI FET device100 through a phase-shift circuit, similar to the example of FIG. 43. Inthe example of FIG. 44, a substrate bias network 152 can be configuredto allow application of a DC control voltage (V_control) to the contactlayer. Such V_control can be applied directly to the contact layer, orthrough a resistance R1 (e.g., a resistor).

FIGS. 45-48 show non-limiting examples in which various couplingsbetween a contact layer of an SOI FET device and another node of the SOIFET device can include a diode. Such a diode can be implemented to, forexample, provide voltage-dependent couplings.

FIG. 45A shows an example that is similar to the example of FIG. 42, butwith a diode D in series with the resistance R. In some embodiments,such a coupling between the contact layer the gate node can beimplemented with or without the resistance R.

FIG. 45B shows that in some embodiments, the polarity of the diode D canbe reversed from the example of FIG. 45A. It will be understood thatsuch polarity reversal of the diode can also be implemented in theexamples of FIGS. 46-48.

FIG. 46 shows an example that is similar to the example of FIG. 43, butwith a diode D in parallel with a phase-shifting circuit (e.g., acapacitance C). In some embodiments, such a coupling between the contactlayer and the gate node can be implemented with or without theresistance R.

FIG. 47 shows an example that is similar to the example of FIG. 42, butwith a diode D in series with the resistance R. In some embodiments, aDC control voltage (V_control) can be applied directly to the contactlayer, or through a resistance (e.g., a resistor).

FIG. 48 shows an example that is similar to the example of FIG. 46, butwith biasing. Such biasing can be configured to allow application of aDC control voltage (V_control) to the contact layer directly or througha resistance R (e.g., a resistor).

In some embodiments, a contact layer connection having one or morefeatures as described herein can be utilized to sense a voltagecondition of the substrate. Such a sensed voltage can be utilized to,for example, compensate the voltage condition. For example, charge canbe driven into or out of the substrate as needed or desired through thecontact layer.

FIG. 49 shows an SOI FET device 100 having a contact layer as describedherein. Such a contact layer can be utilized to sense a voltage Vassociated with the substrate node. FIGS. 50-57 show non-limitingexamples of how such sensed voltage can be utilized in various feedbackand/or biasing configurations. Although various examples are describedin the context of voltage V, it will be understood that one or morefeatures of the present disclosure can also be implemented utilizing,for example, sensed current associated with the substrate.

FIGS. 50A-50D show examples of how a contact layer of an SOI FET device100 can be coupled to another node of the SOI FET device 100. In someembodiments, such couplings can be utilized to facilitate the foregoingcompensation based on the sensed substrate voltage of FIG. 49. FIG. 50Ashows that a coupling 190 can be implemented between the contact layerand a gate node. FIG. 50B shows that a coupling 190 can be implementedbetween the contact layer and a body node. FIG. 50C shows that acoupling 190 can be implemented between the contact layer and a sourcenode. FIG. 50D shows that a coupling 190 can be implemented between thecontact layer and a drain node. In some embodiments, the contact layercan be coupled to more than one of the foregoing nodes.

FIGS. 51A-51D show examples of how a contact layer of an SOI FET device100 can be coupled to another node of the SOI FET device 100 through aphase-shifting circuit (e.g., a capacitance) 192. In some embodiments,such couplings can be utilized to facilitate the foregoing compensationbased on the sensed substrate voltage of FIG. 49. FIG. 51A shows that acoupling 190 having a phase-shifting circuit 192 can be implementedbetween the contact layer and a gate node. FIG. 51 B shows that acoupling 190 having a phase-shifting circuit 192 can be implementedbetween the contact layer and a body node. FIG. 51C shows that acoupling 190 having a phase-shifting circuit 192 can be implementedbetween the contact layer and a source node. FIG. 51 D shows that acoupling 190 having a phase-shifting circuit 192 can be implementedbetween the contact layer and a drain node. In some embodiments, thecontact layer can be coupled to more than one of the foregoing nodes.

FIGS. 52A-52D show examples that are similar to the examples of FIGS.50A-50D. However, in each of the examples of FIGS. 52A-52D, a biassignal such as a DC control voltage (V_control) can be applied to thecontact layer. Such V_control can be applied to the contact layerdirectly or through a resistance.

FIGS. 53A-53D show examples that are similar to the examples of FIGS.51A-51D. However, in each of the examples of FIGS. 53A-53D, a biassignal such as a DC control voltage (V_control) can be applied to thecontact layer. Such V_control can be applied to the contact layerdirectly or through a resistance.

FIGS. 54A-54D show examples of how a contact layer of an SOI FET device100 can be coupled to another node of the SOI FET device 100 through adiode D. In some embodiments, such couplings can be utilized tofacilitate the foregoing compensation based on the sensed substratevoltage of FIG. 49. In some embodiments, a given diode can be reversedfrom the configuration as shown as needed or desired.

FIG. 54A shows that a coupling 190 having a diode D can be implementedbetween the contact layer and a gate node. FIG. 54B shows that acoupling 190 having a diode D can be implemented between the contactlayer and a body node. FIG. 54C shows that a coupling 190 having a diodeD can be implemented between the contact layer and a source node. FIG.54D shows that a coupling 190 having a diode D can be implementedbetween the contact layer and a drain node. In some embodiments, thecontact layer can be coupled to more than one of the foregoing nodes.

FIGS. 55A-55D show examples of how a contact layer of an SOI FET device100 can be coupled to another node of the SOI FET device 100 through adiode D and a phase-shifting circuit 192. In some embodiments, suchdiode D and the phase-shifting circuit 192 can be arranged in a parallelconfiguration. In some embodiments, such couplings can be utilized tofacilitate the foregoing compensation based on the sensed substratevoltage of FIG. 49. In some embodiments, a given diode can be reversedfrom the configuration as shown as needed or desired.

FIG. 55A shows that a coupling 190 having a diode D and a phase-shiftingcircuit 190 can be implemented between the contact layer and a gatenode. FIG. 55B shows that a coupling 190 having a diode D and aphase-shifting circuit 190 can be implemented between the contact layerand a body node. FIG. 55C shows that a coupling 190 having a diode D anda phase-shifting circuit 190 can be implemented between the contactlayer and a source node. FIG. 55D shows that a coupling 190 having adiode D and a phase-shifting circuit 190 can be implemented between thecontact layer and a drain node. In some embodiments, the contact layercan be coupled to more than one of the foregoing nodes.

FIGS. 56A-56D show examples that are similar to the examples of FIGS.54A-54D. However, in each of the examples of FIGS. 56A-56D, a biassignal such as a DC control voltage (V_control) can be applied to thecontact layer. Such V_control can be applied to the contact layerdirectly or through a resistance.

FIGS. 57A-57D show examples that are similar to the examples of FIGS.55A-55D. However, in each of the examples of FIGS. 57A-57D, a biassignal such as a DC control voltage (V_control) can be applied to thecontact layer. Such V_control can be applied to the contact layerdirectly or through a resistance.

Examples Related to Switch Configurations

As described herein in reference to the examples of FIGS. 29, 30 and33-37, FET devices having one or more features of the present disclosurecan be utilized to implement an SPDT switch configuration. It will beunderstood that FET devices having one or more features of the presentdisclosure can also be implemented in other switch configurations.

FIGS. 58-68 show examples related to various switch configurations thatcan be implemented utilizing FET devices such as SOI FET devices havingone or more features as described herein. For example, FIG. 58 shows aswitch assembly 255 implemented in a single-pole-single-throw (SPST)configuration. Such a switch can include an SOI FET device 100implemented between a first port (Port1) and a second port (Port2).

FIG. 59 shows that in some embodiments, the SOI FET device 100 of FIG.58 can include a contact layer feature as described herein. The sourcenode of the SOI FET device 100 can be connected to the first port(Port1), and the drain node of the SOI FET device 100 can be connectedto the second port (Port2). As described herein, the SOI FET device 100can be turned ON to close the switch 255 (of FIG. 58) between the twoports, and turned OFF to open the switch 250 between the two ports.

It will be understood that the SOI FET device 100 of FIGS. 58 and 59 caninclude a single FET, or a plurality of FETs arranged in a stack. Itwill also be understood that each of various SOI FET devices 100 ofFIGS. 60-68 can include a single FET, or a plurality of FETs arranged ina stack.

FIG. 60 shows an example of how two SPST switches (e.g., similar to theexamples of FIGS. 58, 59) having one or more features as describedherein can be utilized to form a switch assembly 255 having asingle-pole-double-throw (SPDT) configuration. FIG. 61 shows, in a SPDTrepresentation, that the switch assembly 255 of FIG. 60 can be utilizedin an antenna switch configuration 265. It will be understood that oneor more features of the present disclosure can also be utilized inswitching applications other than antenna switching application.

It is noted that in various switching configuration examples of FIGS.58-68, switchable shunt paths are not shown for simplified views of theswitching configurations. Accordingly, it will be understood that someor all of switchable paths in such switching configurations may or maynot have associated with them switchable shunt paths (e.g., similar tothe examples of FIGS. 29, 30 and 33-37).

Referring to the examples of FIGS. 60 and 61, it is noted that suchexamples are similar to the examples described herein in reference toFIGS. 29, 30 and 33-37. In some embodiments, the single pole (P) of theswitch assembly 250 of FIG. 60 can be utilized as an antenna node (Ant)of the antenna switch 265, and the first and second throws (T1, T2) ofthe switch assembly 255 of FIG. 60 can be utilized as TRx1 and TRx2nodes, respectively, of the antenna switch 265. Although each of theTRx1 and TRx2 nodes is indicated as providing transmit (Tx) and receive(Rx) functionalities, it will be understood that each of such nodes canbe configured to provide either or both of such Tx and Rxfunctionalities.

In the examples of FIGS. 60 and 61, the SPDT functionality is shown tobe provided by two SPST switches 100 a, 100 b, with the first SPSTswitch 100 a providing a first switchable path between the pole P (Antin FIG. 61) and the first throw T1 (TRx1 in FIG. 61), and the secondSPST switch 100 b providing a second switchable path between the pole P(Ant in FIG. 61) and the second throw T2 (TRx2 in FIG. 61). Accordingly,selective coupling of the pole (Ant) with either of the first throw T1(TRx1) and the second throw T2 (TRx2) can be achieved by selectiveswitching operations of the first and second SPST switches. For example,if a connection is desired between the pole (Ant) and the first throw T1(TRx1), the first SPST switch 100 a can be closed, and the second SPSTswitch 100 b can be opened. Similarly, and as depicted in the examplestate in FIGS. 60 and 61, if a connection is desired between the pole(Ant) and the second throw T2 (TRx2), the first SPST switch 100 a can beopened, and the second SPST switch 100 b can be closed.

In the foregoing switching examples of FIGS. 60 and 61, a single TRxpath is connected to the antenna (Ant) node in a given switchconfiguration. It will be understood that in some applications (e.g.,carrier-aggregation applications), more than one TRx paths may beconnected to the same antenna node. Thus, in the context of theforegoing switching configuration involving a plurality of SPSTswitches, more than one of such SPST switches can be closed to therebyconnect their respective throws (TRx nodes) to the same pole (Ant).

FIG. 62 shows an example of how three SPST switches (e.g., similar tothe examples of FIGS. 58, 59) having one or more features as describedherein can be utilized to form a switch assembly 255 having asingle-pole-triple-throw (SP3T) configuration. FIG. 63 shows, in a SP3Trepresentation, that the switch assembly 255 of FIG. 62 can be utilizedin an antenna switch configuration 265. It will be understood that oneor more features of the present disclosure can also be utilized inswitching applications other than antenna switching application.

Referring to the examples of FIGS. 62 and 63, it is noted that the SP3Tconfiguration can be an extension of the SPDT configuration of FIGS. 60and 61. For example, the single pole (P) of the switch assembly 255 ofFIG. 62 can be utilized as an antenna node (Ant) of the antenna switch265, and the first, second and third throws (T1, T2, T3) of the switchassembly 255 of FIG. 62 can be utilized as TRx1, TRx2 and TRx3 nodes,respectively, of the antenna switch 265. Although each of the TRx1, TRx2and TRx3 nodes is indicated as providing transmit (Tx) and receive (Rx)functionalities, it will be understood that each of such nodes can beconfigured to provide either or both of such Tx and Rx functionalities.

In the examples of FIGS. 62 and 63, the SP3T functionality is shown tobe provided by three SPST switches 100 a, 100 b, 100 c, with the firstSPST switch 100 a providing a first switchable path between the pole P(Ant in FIG. 63) and the first throw T1 (TRx1 in FIG. 63), the secondSPST switch 100 b providing a second switchable path between the pole P(Ant in FIG. 63) and the second throw T2 (TRx2 in FIG. 63), and thethird SPST switch 100 c providing a third switchable path between thepole P (Ant in FIG. 63) and the third throw T3 (TRx3 in FIG. 63).Accordingly, selective coupling of the pole (Ant) with one of the firstthrow T1 (TRx1), the second throw T2 (TRx2), and the third throw T3(TRx3) can be achieved by selective switching operations of the first,second and third SPST switches. For example, if a connection is desiredbetween the pole (Ant) and the first throw T1 (TRx1), the first SPSTswitch 100 a can be closed, and each of the second and third SPSTswitches 100 b, 100 c can be opened. If a connection is desired betweenthe pole (Ant) and the second throw T2 (TRx2), the second SPST switch100 b can be closed, and each of the first and third SPST switches 100a, 100 c can be opened. Similarly, and as depicted in the example statein FIGS. 62 and 63, if a connection is desired between the pole (Ant)and the third throw T3 (TRx3), each of the first and second SPSTswitches 100 a, 100 b can be opened, and the third SPST switch 100 c canbe closed.

In the foregoing switching examples of FIGS. 62 and 63, a single TRxpath is connected to the antenna (Ant) node in a given switchconfiguration. It will be understood that in some applications (e.g.,carrier-aggregation applications), more than one TRx paths may beconnected to the same antenna node. Thus, in the context of theforegoing switching configuration involving a plurality of SPSTswitches, more than one of such SPST switches can be closed to therebyconnect their respective throws (TRx nodes) to the same pole (Ant).

Based on the foregoing examples of SPST, SPDT and SP3T configurations ofFIGS. 58-63, one can see that other switching configurations involving asingle pole (SP) can be implemented utilizing SOI FET devices having oneor more features as described herein. Thus, it will be understood that aswitch having a SPNT can be implemented utilizing one or more SOI FETdevices as described herein, where the quantity N is a positive integer.

Switching configurations of FIGS. 60-63 are examples where a single pole(SP) is connectable to one or more of a plurality of throws to providethe foregoing SPNT functionality. FIGS. 64-67 show examples where morethan one poles can be provided in switching configurations. FIGS. 64 and65 show examples related to a double-pole-double-throw (DPDT) switchingconfiguration that can utilize a plurality of SOI FET devices having oneor more features as described herein. Similarly, FIGS. 66 and 67 showexamples related to a triple-pole-triple-throw (3P3T) switchingconfiguration that can utilize a plurality of SOI FET devices having oneor more features as described herein.

It will be understood that a switching configuration utilizing aplurality of SOI FET devices having one or more features as describedherein can include more than three poles. Further, it is noted that inthe examples of FIGS. 64-67, the number of throws (e.g., 2 in FIGS. 64and 65, and 3 in FIGS. 66 and 67) are depicted as being the same as thecorresponding number of poles for convenience. However, it will beunderstood that the number of throws may be different than the number ofpoles.

FIG. 64 shows an example of how four SPST switches (e.g., similar to theexamples of FIGS. 58, 59) having one or more features as describedherein can be utilized to form a switch assembly 255 having a DPDTconfiguration. FIG. 65 shows, in a DPDT representation, that the switchassembly 255 of FIG. 64 can be utilized in an antenna switchconfiguration 265. It will be understood that one or more features ofthe present disclosure can also be utilized in switching applicationsother than antenna switching application.

In the examples of FIGS. 64 and 65, the DPDT functionality is shown tobe provided by four SPST switches 100 a, 100 b, 100 c, 100 d. The firstSPST switch 100 a is shown to provide a switchable path between a firstpole P1 (Ant1 in FIG. 65) and a first throw T1 (TRx1 in FIG. 65), thesecond SPST switch 100 b is shown to provide a switchable path between asecond pole P2 (Ant2 in FIG. 65) and the first throw T1 (TRx1 in FIG.65), the third SPST switch 100 c is shown to provide a switchable pathbetween the first pole P1 (Ant1 in FIG. 65) and a second throw T2 (TRx2in FIG. 65), and the fourth SPST switch 100 d is shown to provide aswitchable path between the second pole P2 (Ant2 in FIG. 65) and thesecond throw T2 (TRx2 in FIG. 65). Accordingly, selective couplingbetween one or more of the poles (antenna nodes) with one or more of thethrows (TRx nodes) can be achieved by selective switching operations ofthe four SPST switches 100 a, 100 b, 100 c, 100 d. Examples of suchswitching operations are described herein in greater detail.

FIG. 66 shows an example of how nine SPST switches (e.g., similar to theexamples of FIGS. 58, 59) having one or more features as describedherein can be utilized to form a switch assembly 255 having a 3P3Tconfiguration. FIG. 67 shows, in a 3P3T representation, that the switchassembly 255 of FIG. 66 can be utilized in an antenna switchconfiguration 265. It will be understood that one or more features ofthe present disclosure can also be utilized in switching applicationsother than antenna switching application.

Referring to the examples of FIGS. 66 and 67, it is noted that the 3P3Tconfiguration can be an extension of the DPDT configuration of FIGS. 64and 65. For example, a third pole (P3) can be utilized as a thirdantenna node (Ant3), and a third throw (T3) can be utilized as a thirdTRx node (TRx3). Connectivity associated with such third pole and thirdthrow can be implemented similar to the examples of FIGS. 64 and 65.

In the examples of FIGS. 66 and 67, the 3P3T functionality is shown tobe provided by nine SPST switches 100 a-100 i. Such nine SPST switchescan provide switchable paths as listed in Table 1.

TABLE 1 SPST switch Pole Throw 100a P1 T1 100b P2 T1 100c P3 T1 100d P1T2 100e P2 T2 100f P3 T2 100g P1 T3 100h P2 T3 100i P3 T3

Based on the example of FIGS. 66 and 67, and Table 1, one can see thatselective coupling between one or more of the poles (antenna nodes) withone or more of the throws (TRx nodes) can be achieved by selectiveswitching operations of the nine SPST switches 100 a-100 i.

In many applications, switching configurations having a plurality ofpoles and a plurality of throws can provide increased flexibility in howRF signals can be routed therethrough. FIGS. 68A-68E show examples ofhow a DPDT switching configuration such as the examples of FIGS. 64 and65 can be operated to provide different signal routing functionalities.It will be understood that similar control schemes can also beimplemented for other switching configurations, such as the 3P3Texamples of FIGS. 66 and 67.

In some wireless front-end architectures, two antennas can be provided,and such antennas can operate with two channels, with each channel beingconfigured for either or both of Tx and Rx operations. For the purposeof description, it will be assumed that each channel is configured forboth Tx and Rx operations (TRx). However, it will be understood thateach channel does not necessarily need to have such TRx functionality.For example, one channel can be configured for TRx operations, while theother channel can be configured for Rx operation. Other configurationsare also possible.

In the foregoing front-end architectures, there may be relatively simpleswitching states including a first state and a second state. In thefirst state, the first TRx channel (associated with the node TRx1) canoperate with the first antenna (associated with the node Ant1), and thesecond TRx channel (associated with the node TRx2) can operate with thesecond antenna (associated with the node Ant2). In the second state,connections between the antenna nodes and the TRx nodes can be swappedfrom the first state. Accordingly, the first TRx channel (associatedwith the node TRx1) can operate with the second antenna (associated withthe node Ant2), and the second TRx channel (associated with the nodeTRx2) can operate with the first antenna (associated with the nodeAnt1).

In some embodiments, such two states of the DPDT switching configurationcan be controlled by a one-bit logic scheme, as shown in the examplelogic states in Table 2.

TABLE 2 Control TRx1-Ant1 TRx1-Ant2 TRx2-Ant1 TRx2-Ant2 State logicconnection connection connection connection 1 0 Yes No No Yes 2 1 No YesYes No

The first state (State 1) of the example of Table 2 is depicted in FIG.68A as 271 a, where the TRx1-Ant1 connection is indicated as path 275 a,and the TRx2-Ant2 connection is indicated as path 277 a. A controlsignal, representative of the control logic of Table 2, provided to theassembly (273) of the four SPST switches (100 a, 100 b, 100 c, 100 d) iscollectively indicated as Vc(s). Similarly, the second state (State 2)of the example of Table 2 is depicted in FIG. 68B as 271 b, where theTRx1-Ant2 connection is indicated as path 277 b, and the TRx2-Ant1connection is indicated as path 275 b.

In some front-end architectures having a DPDT switching configuration,it may be desirable to have additional switching states. For example, itmay be desirable to have only one path active among the two TRx channelsand the two antennas. In another example, it may be desirable to disableall signal paths through the DPDT switch. Examples of 3-bit controllogic that can be utilized to achieve such examples switching states arelisted in Table 3.

TABLE 3 Control logic TRx1-Ant1 TRx1-Ant2 TRx2-Ant1 TRx2-Ant2 State(Vc1, Vc2, Vc3) connection connection connection connection 1 0, 0, 0 NoNo No No 2 0, 0, 1 Yes No No Yes 3 0, 1, 0 Yes No No No 4 0, 1, 1 No YesYes No 5 1, 0, 0 No Yes No No

The first state (State 1) of the example of Table 3 is depicted in FIG.68E as 271 e, where all of the TRx-Ant paths are disconnected. A controlsignal indicated as Vc(s) in FIG. 68E and as listed in Table 3 can beprovided to the assembly (272) of the four SPST switches (100 a, 100 b,100 c, 100 d) to effectuate such a switching state.

The second state (State 2) of the example of Table 3 is depicted in FIG.68A as 271 a, where the TRx1-Ant1 connection is indicated as path 275 a,and the TRx2-Ant2 connection is indicated as path 277 a. A controlsignal indicated as Vc(s) in FIG. 68A and as listed in Table 3 can beprovided to the assembly (273) of the four SPST switches (100 a, 100 b,100 c, 100 d) to effectuate such a switching state.

The third state (State 3) of the example of Table 3 is depicted in FIG.68C as 271 c, where the TRx1-Ant1 connection is indicated as path 275 c,and all other paths are disconnected. A control signal indicated asVc(s) in FIG. 68C and as listed in Table 3 can be provided to theassembly (273) of the four SPST switches (100 a, 100 b, 100 c, 100 d) toeffectuate such a switching state.

The fourth state (State 4) of the example of Table 3 is depicted in FIG.68B as 271 b, where the TRx1-Ant2 connection is indicated as path 277 b,and the TRx2-Ant1 connection is indicated as path 275 b. A controlsignal indicated as Vc(s) in FIG. 68B and as listed in Table 3 can beprovided to the assembly (273) of the four SPST switches (100 a, 100 b,100 c, 100 d) to effectuate such a switching state.

The fifth state (State 5) of the example of Table 3 is depicted in FIG.68D as 270 d, where the TRx1-Ant2 connection is indicated as path 277d,and all other paths are disconnected. A control signal indicated asVc(s) in FIG. 68D and as listed in Table 3 can be provided to theassembly (273) of the four SPST switches (100 a, 100 b, 100 c, 100 d) toeffectuate such a switching state.

As one can see, other switching configurations can also be implementedwith the DPDT switch of FIGS. 68A-68E. It will also be understood thatother switches such as 3P3T of FIGS. 66 and 67 can be controlled bycontrol logic in a similar manner.

Cavity Formation

Electrical interference between devices/components of an electroniccircuit or device can lead to non-linearity that can negatively impactperformance. For example, certain components of an SOI or other type ofsemiconductor structure may be susceptible to cross-talk withneighboring electrical components laterally and/or vertically throughsemiconductor substrate or other layer/component. In certainembodiments, SOI and/or other types of semiconductor devices may includecontacts for electrically connecting to passive elements, such asinductors, capacitors, or the like, which may generally have performancefactor, or Q value, characteristics that provide a measurement of theirefficiency. Maximizing the Q value can be achieved through minimizingboth the resistance of the passive device (e.g., inductor) as well asthe energy loss into the substrate and surrounding dielectric materialwhen energized.

The use of low dielectric constant (i.e., low-k) materials in theconstruction of planar inductor coils may be used to at least partiallydecrease the radio frequency (RF) energy lost into the surroundingmaterial, thus improving the inductor Q value, especially at relativelyhigh frequencies. In certain embodiments, relatively highly-engineeredsubstrates, rather than traditional bulk substrate in layer-transferprocesses, may be implemented to at least partially reduce parasiticbulk capacitance and/or improve active device linearity.

The formation of cavities in semiconductor device structures may also beused in semiconductor processing to replace at least some of thematerial surrounding inductors, laterally and/or vertically, with air orvacuum, which may exhibit substantially low k value characteristics(e.g., ≈1), thereby potentially reducing RF loss when such cavities arestrategically placed around or near certain circuit elements; cavitiesmay improve both passive and active device performance. The term“cavity” is used herein according to its broad and ordinary meaning andmay refer to any space (e.g., three-dimensional space) or region thatcontains air or vacuum contained within one or more physical barriers;generally, a cavity may not have semiconductor substrate or dielectricdisposed therein, at least in a region characterized as the cavity.

In certain embodiments, cavities are formed at the wafer-level, orduring wafer level packaging, using certain processing techniques.Additionally or alternatively, cavities may be created in the interfacelayer, during layer-transfer processing, using various approaches. Forexample, disclosed herein are devices and methods associated with thecreation of cavities nearby critical passive elements by creating themabove and/or underneath such elements at least in part at the die level(e.g., after wafer singulation). Such cavity formation may be achievedin a dual layer transfer process beginning after backside thinning whilestill mounted to a temporary carrier wafer. For example, FIGS. 69A and69B show processes 3700A, 3700B that can be implemented to form one ormore cavities in an SOI device or structure having one or more featuresas described herein. The embodiments shown in FIGS. 69A and 69B mayprovide for die-level cavity creation under one or more passive (oractive) elements of an SOI device structure using dual layer transfer.FIGS. 70A and 70B show examples of various stages of the fabricationprocesses of FIGS. 69A and 69B, respectively.

At block 3702, the process 3700A involves providing an SOI wafer, orportion thereof, having one or more devices and/or connections, as shownat stage 3802. The associated example structure 3802 may correspond tocertain SOI processes disclosed above. Specifically, the structure 3802may include one or more of a bulk substrate 3806, buried oxide (BOX)layer 3804, active semiconductor device(s) 3850, through-BOX via(s)3808, electrical connections (e.g., metal stack) 3810, passivation layer3814, passive or active electrical element(s) (e.g., inductor, terminal,etc.) 3812, and/or handle wafer 3816. The handle wafer 3816 may be addedto create mechanical stability for one or more steps in the process. Incertain embodiments, the handle wafer 3816 may be intended as atemporary structural feature for use in one or more processing steps.The handle wafer 3816 may be glued on top of the passivation layer 3814.With the handle wafer 2816 and the substrate 3806, the device 3802 mayat least temporarily have a double-wafer structure, wherein the process3700A-3700B comprises a double-layer transfer process with transfer tothe handle wafer 3816, and later to a replacement substrate 3807. Thepassivation layer/area 3814 may comprise one or more dielectric layers.In certain contexts, an upper-most layer or portion of the one or moredielectric layers that make up the passivation layer/area 3814 may bereferred to as a/the passivation layer.

The substrate layer 3806 may further provide stability to the structure3802, thereby allowing for certain of the remaining layers that may notbe formable without being associated with a mechanically stabilizingsubstrate/wafer. For example, in certain embodiments, the passivationlayer/area 3814 may be approximately 10 μm thick, or thinner (e.g., 2-10μm thick) wherein the substrate layer 3806 is substantially thicker(e.g., approximately 600 μm think) to provide mechanical stability tothe passivation layer 3814 and associated components.

In certain embodiments, wherein a plurality of elements are printed on asingle die/chip, it may be desirable to at least partially prevent orreduce cross-talk between such elements. For example, separate elementsmay cross-talk through the substrate layer 3806, one or more componentscarrying RF signal(s) may capacitively couple to the substrate 3806,such that the substrate 3806 may carry such signal(s) laterally andcouple to neighboring elements, possibly leading to performancedegradation.

At block 3704, the process 3700A involves at least partially removingthe backside substrate layer 3806. For example, as shown in structure3803, the backside substrate 3806 may be thinned substantiallycompletely to expose the backside of the BOX layer 3804. At block 3706,the process 3700A involves applying a sacrificial material 3870 to thebackside of the box layer 3804. The sacrificial material 3870 may bepatterned to form shape/form corresponding to a desired future cavity.In certain embodiments, the sacrificial material 3870 may be intended asa temporary structural filler that may be sublimated out in connectionwith a subsequent processing step.

Sacrificial material, as described herein may comprise oxide, nitride,or a combination of oxide and nitride. Sacrificial material according toembodiments disclosed herein may be any material that may be reactivewith dry and/or wet etch chemistries, such as with relatively highselectivity to certain surrounding materials. For example, low-densityoxides and/or nitrides may be used. In certain embodiments, sacrificialmaterial may comprises one or more reactive metals (e.g., Cu, Al). Inmay be advantageous for sacrificial material to comprise a material thatmay be sublimated from a solid to a gas under vacuum and/or heatconditions.

As the sacrificial material 3870 provides a form that will later beoccupied by a cavity feature, the positioning of the sacrificialmaterial 3870 may be implemented to achieve desired RF isolation in thesemiconductor die. For example, the sacrificial material/cavity may bedisposed at least partially under a passive device or element, and/or anactive element, depending on the isolation needs of the circuit.Therefore, the patterned material/cavity 3870 may be disposed in regionswhere improved linearity performance is desired.

The thinned wafer 3805 may undergo photo image processing to define thedesirable pattern in the sacrificial material 3870 where the cavity isdesired, including one or more channels running from the form/cavity tothe edge of the die, all of which may be removed later in the process.

Although illustrated in certain position under the oxide layer, thepatterned form of sacrificial material 3870 may be disposed at anydesirable location or in any desirable shape or form. For example, theform 3870 may advantageously be under the active device 3850, at leastpartially.

FIG. 71A shows a plan view of a die 3900 showing an embodiment of alayout of sacrificial material, such as that shown in structure 3805.The die 3900 may comprise a plurality of transistor devices, capacitors,inductors and/or other devices, which may be electrically accessible viaone or more contacts 3912. The various devices of the die 3900 maycorrespond to certain distinct circuit blocks that may desirable toisolate at least in part from one another. The die 3900 may representone of thousands of distinct partitioned elements of a wafer structureprior to die singulation, wherein individual dies are physicallycut/separated from the larger wafer structure.

FIG. 71A shows a patterning/sacrificial material 3970, which maycorrespond to the material 3870 shown in FIG. 70A. The material 3970 mayinclude one or more channel portions 3971, which may provide a path forremoval/escape of the material 3970 at a subsequent processing step tothereby form one or more RF isolation cavities, as described herein. Theillustrated channel(s) are not necessarily drawn to scale, and it shouldbe understood that sacrificial material, as described herein, may beapplied/patterned according to any desirable or practical shape ordesign. The channel(s) 3971 may be designed to run into channelspositioned on a wafer between adjacent dies. The channel(s) 3971 mayallow for vaporization of the material 3970 out of the edge of thedie/wafer, which may take place after die singulation.

The process 3700B may involve applying an interface layer 3860 at leastpartially over the sacrificial material 3870 at block 3780. Theinterface layer may be, for example, an adhesive, borosilicon glass,silicon, or other type of material. In certain embodiments, theinterface layer 3860 may be used as an attachment medium for attaching areplacement substrate (see structure 3811) and/or to provide structuralprotection for the cavity to be formed. The interface layer 3860 may bea planarizing interface layer, and may be thicker than the sacrificiallayer 3870 in at least the region adjacent to the patterned material3870. The interface layer 3860 may be applied to the wafer backside ontop of the sacrificial material 3870, wherein the wafer may besubsequently bonded (e.g., permanently) to a new replacement substrate3807, as shown in structure 3811 and step 3710 of the process 3700B.

Replacement substrates, as described in connection with variousembodiments disclosed herein, may comprise any suitable or desirablematerial. For example, a replacement substrate may comprise silicon,glass, or other material or combination of materials.

Singulation of the die associated with the structures illustrated inFIGS. 70A and 70B may be performed after removal of the temporarycarrier substrate 3806. When individual dies are singulated, portion(s)of the sacrificial layer 3870 may be at least partially exposed in thevertical face in one or more locations along the edge of the die,wherein the sacrificial material 3870 may be removed therefrom. Variousmethods of removing the sacrificial material may be implemented withinthe scope of the present disclosure. For example, selective wet and/ordry etching, or sublimation, may be employed, removing at least part ofthe material 3870 underneath the desired circuit elements fabricated onthe wafer through the access route(s) leading to the material/cavity.Once the sacrificial material 3870 has been removed, a cavity 3875comprising air in the locations the sacrificial material had previouslyoccupied may remain.

The replacement substrate 3807 may comprise any material that providessubstantially adequate stability for the structure 3811. Selection ofsubstrate material may depend on one or more factors, such as thicknessof the interface layer, for example. The characteristics of thereplacement substrate 3807 may affect performance linearity to somedegree; it may be advantageous for the substrate 3807 to have relativelyhigh resitivity characteristics, and therefore silicon or glass may beutilized in certain embodiments. In the examples of FIGS. 69A-69B and70A-70B, it will be understood that the various blocks, or stages, mayor may not be performed in the example sequences illustrated.Furthermore, various of the illustrated/described steps may be omittedin certain embodiments, or additional steps may be implemented that arenot explicitly described while remaining within the scope of the presentdisclosure.

FIG. 71B shows a resulting cavity 3975, which may correspond to thecavity 3875 shown in FIG. 70B, where the sacrificial material has beenevacuated from the die to form the cavity.

Similarly to the cavity formation processes described above, cavitiescan be created in single-layer transfer process, which may beimplemented once front-side processing has been completed. FIGS. 72A and72B show processes 4000A, 4000B that can be implemented to form one ormore cavities in an SOI device or structure having one or more featuresas described herein. FIGS. 73A-1 and 73B-1 show examples of variousstages/structures of the fabrication processes of FIGS. 72A and 72B,respectively. The embodiments disclosed in FIGS. 72A-72B and 73A-1-73B-1may be implemented to provide die-level cavity creation above certainelectrical element(s), such as passive element(s) of an SOI device usingsingle layer transfer. In the examples of FIGS. 72A-72B and 73A-1-73B-1,it will be understood that the various blocks, or stages, may or may notbe performed in the example sequences illustrated. Furthermore, variousof the illustrated/described steps may be omitted in certainembodiments, or additional steps may be implemented that are notexplicitly described while remaining within the scope of the presentdisclosure.

While described above are processes and embodiments for patterning for atransfer to the backside of a wafer, the description below in connectionwith FIGS. 72A-72B and 73A-1-73B-1 may describe patterning for transferto the front-side of a wafer. At block 4002, the process 4000A involvesproviding at least a portion of a SOI wafer or die having one or moredevices and/or connections formed or otherwise associated therewith, asdescribed in various embodiments above. Certain of the featuresillustrated in FIGS. 73A-1 and 73B-1 may be similar in certain respectsto certain features illustrated in figures described above, andtherefore, for simplicity, detailed description of such features may notbe provided here.

The structure 4102 may include an electrical element 4112 that may be inelectrical contact with the FET(s) 4150 and or one or more othercomponents of the device. For example, the electrical element 4112 maybe a passive device, such as an inductor, capacitor, or the like. Theelectrical element 4112 may represent a metal structure or devicedesigned to lie on a top surface of the wafer structure 4102. Theprocesses 4000A and 4000B may further involve progressively burying theelement 4112 at least partially inside a cavity to provide RF isolationas described herein.

The electrical element 4112 may be, for example, a passive device, suchas an inductor or capacitor, or alternatively a switching device, asurface acoustic wave (SAW) device, or a bulk acoustic wave (BAW)device, or a film bulk acoustic resonator (FBAR) device.

At block 4004, a sacrificial material 4170 may be patterned and appliedto the passivation layer 4114 on the front-side of the wafer. The waferstructure 4103 may undergo photo image processing to define a pattern inthe sacrificial material 4170 where a cavity is desired to be formed.Furthermore, one or more lines or channels running from the cavity tothe edge of the die may also be formed, wherein the sacrificial material4170 is intended to be at least partially removed later in the process.

At block 4006, an interface layer 4160 may applied over the sacrificialmaterial 4170 on the front side of the wafer, and further a handle waferstructure 4116 may be bonded to at least a portion of the interfacelayer 4160. The interface layer 4160 may be a planarizing interfacelayer that is thicker than the sacrificial layer at least in certainportions. The handle wafer 4116 may be applied to the wafer front-sideof the wafer structure 4106 on top of the sacrificial material 4170. Incertain embodiments, the wafer is permanently bonded to a new carrier.

FIG. 74A shows a plan view of a die 4200 showing an embodiment of alayout of sacrificial material, such as that shown in structure 4106.The die 4200 may comprise a plurality of transistor devices, capacitors,inductors and/or other devices, which may be electrically accessible viaone or more contacts 4212. The various devices of the die 4200 maycorrespond to certain distinct circuit blocks that may desirable toisolate at least in part from one another. FIG. 74A shows apatterning/sacrificial material 4270, which may correspond to thematerial 4170 shown in FIG. 72A. The material 4270 may include one ormore channel portions 4271, which may provide a path for removal/escapeof the material 4270 at a subsequent processing step to thereby form oneor more RF isolation cavities, as described herein. The illustratedchannel(s) are not necessarily drawn to scale, and it should beunderstood that sacrificial material, as described herein, may beapplied/patterned according to any desirable or practical shape ordesign. The channel(s) 4271 may be designed to run into channelspositioned on a wafer between adjacent dies. The channel(s) 4271 mayallow for vaporization of the material 4270 out of the edge of thedie/wafer, which may take place after die singulation.

At block 4008, the process 4000B involves removing some or all of thebackside substrate 4106, which may expose at least a portion of theoxide layer 4104 on the backside of the wafer. Substrate removal may beachieved through a back-grind thinning process, which may exposethrough-BOX metal via(s) 4108, which can subsequently be contacted usingany suitable method to create a circuit contact on the backside of theoriginal semiconductor wafer. Specifically, block 4010 of the process4000B involves creating an electrical contact 4113 to the through-oxidevia 4108 on the backside of the wafer. The electrical contact 4113 maybe desirable for providing electrical contact to the active device(s)4150 when the handle wafer 4116 is present preventing access to theconnections 4110 from the top side.

In certain embodiments, die singulation may occur between process steps4111 and 4112, or before the sacrificial material 4170 is removed toform the cavity 4175. Once the die has been cut/sawed, the channel(s) ofthe sacrificial material may be exposed, wherein the process 4000B mayinvolve heating the material to cause it to evaporate and vacate thecavity, leaving an air-filled cavity in its place. The material removalstep is shown at block 4012, which describes at least partially removingthe sacrificial material 4170 to create the cavity 4175 occupying thevoid left by removal of the material 4170. Various methods of removingthe sacrificial material may be implemented, such as selective wet ordry etching, or sublimation. The sacrificial material 4170 is removedaround the desired circuit elements fabricated on the wafer front-sidethrough the multiple access routes leading to the cavity, leavingisolating space in the locations the sacrificial material had previouslyoccupied.

FIG. 74B shows a resulting cavity 4275, which may correspond to thecavity 4175 shown in FIG. 73B-1 (or FIG. 73B-2, described below), wherethe sacrificial material 4170 has been evacuated from the die to formthe cavity 4175 (4275 in FIG. 74B).

FIGS. 73A-2 and 73B-2 show examples of various stages/structures of thefabrication processes of FIGS. 72A and 72B, respectively, wherein thecavity formation may be implemented such that the cavity 4175 does notnecessarily have an electrical element exposed therein and/or positionedadjacent thereto. In certain embodiments, the form of sacrificialmaterial 4170 and/or cavity 4175 may be positioned at least partiallyabove or over the active FET device(s) 4150.

Certain embodiments disclosed herein provide for the creation of acavity in an interface layer by patterning the interface layer itself.For example, patterning may be done using various establishedphotolithography techniques, prior to bonding the original wafer to itsfinal substrate. FIG. 75 shows a process 4300 that can be implemented toform one or more cavities in an SOI device or structure having one ormore features as described herein. FIGS. 76A and 76B show examples ofvarious stages of the fabrication processes of FIG. 75. In the examplesof FIGS. 75, and 76A and 76B, it will be understood that the variousblocks, or stages, may or may not be performed in the example sequencesillustrated. Furthermore, various of the illustrated/described steps maybe omitted in certain embodiments, or additional steps may beimplemented that are not explicitly described while remaining within thescope of the present disclosure. Certain of the features illustrated inFIGS. 76A and 76B may be similar in certain respects to certain featuresillustrated in figures described above, and therefore, for simplicity,detailed description of such features may not be provided here.

At block 4302, the process 4300 involves providing at least a portion ofan SOI wafer having one or more devices and/or connections formed orotherwise associated therewith, as described in various embodimentsabove. The process 4300 may provide for wafer-level cavity creationabove, for example, a passive element of an SOI device usingsingle-layer transfer. An electrical element 4412, such as a passivedevice, for example (e.g., inductor, capacitor, etc.) may be disposed ona front-side of the wafer structure 4401. At block 4304, an interfacelayer 4460 may be applied over a passivation layer 4414 on thefront-side of the wafer 4403. The interface layer 4460 may be masked toform a window exposing at least a portion of the element 4412. Theinterface layer 4460 may comprise a glue, or adhesive, material that maybe patterned with photo resist. In certain embodiments, the interfacelayer 4460 comprises polyimide, or other high-temperature adhesive or atleast partially amorphous polymer, which may be applied using a spin-onapplication, for example. The opening, or trench, 4474 may be etched ordeveloped away, such as before the interface material is cured. Theinterface layer may be used to permanently bond the handle wafer 4416 tothe device.

The electrical element 4412 may be, for example, a passive device, suchas an inductor or capacitor, or alternatively a switching device, asurface acoustic wave (SAW) device, or a bulk acoustic wave (BAW)device, or a film bulk acoustic resonator (FBAR) device.

In certain embodiments, the window portion 4474 extends through theentire thickness of the interface layer 4460 in at least one or moreportions. Although not illustrated in structure 4403, in certainembodiment, a window or cavity having a thickness that does not extendall the way through the interface layer 4460 may be achievable by firstmasking a first layer of interface material, and applying additionalinterface material (not shown) to a handle wafer structure (e.g., handlewafer 4416) and binding the combined interface layer/handle wafer overthe window. The interface layer 4460 may be photo-imagable or may beapplied and etched away to form the window area 4474.

At block 4306, the process 4300 involves bonding a handle waferstructure 4416 to at least a portion of the interface layer 4460,thereby forming a cavity 4475 over at least a portion of the element4412. At block 4308, the process 4300B involves removing some or all ofthe backside substrate 4406, which may expose at least a portion of theoxide layer 4404 on the backside of the wafer.

At block 4310, the process 4300 may involve creating an electricalcontact 4413 to the through-oxide via 4408 on the backside of the wafer.The contact 4413 may provide electrical contact to the circuit, and maycomprise metal or other electrically-conductive material. In certainembodiments, die singulation may take place after block 4310.

FIG. 76B shows an example of various stages/structures of thefabrication processes of FIG. 75, wherein the trench and/or cavityformation may be implemented such that the trench 4474 and/or cavity4475 do not necessarily have an electrical element exposed thereinand/or positioned adjacent thereto. In certain embodiments, the trench4474 and/or cavity 4475 may be positioned at least partially above orover the active FET device(s) 4450.

FIG. 77 shows a process 4500 that can be implemented to form one or morecavities in an SOI device or structure having one or more features asdescribed herein. The process 4500 may provide for wafer-level cavitycreation below, for example, a passive element of an SOI device usingdual-layer transfer. FIG. 78 shows examples of various stages of thefabrication process of FIG. 77. In the examples of FIGS. 77 and 78, itwill be understood that the various blocks, or stages, may or may not beperformed in the example sequences illustrated. Furthermore, various ofthe illustrated/described steps may be omitted in certain embodiments,or additional steps may be implemented that are not explicitly describedwhile remaining within the scope of the present disclosure. Certain ofthe features illustrated in FIG. 78 may be similar in certain respectsto certain features illustrated in figures described above, andtherefore, for simplicity, detailed description of such features may notbe provided here.

While the process 4300 of FIG. 75 may correspond to cavity formationduring a single layer transfer process, the process 4500 may correspondto cavity formation during a dual-layer transfer process.

At block 4502, the process 4500 involves providing at least a portion ofa SOI wafer having one or more devices and/or connections formed orotherwise associated therewith, as described in various embodimentsabove. At block 4504, the process 4500B involves removing some or all ofthe backside substrate 4605, which may expose at least a portion of theoxide layer 4604 on the backside of the wafer.

At block 4506, the process 4500 involves applying an interface layer4460 on the backside of the wafer, such as in contact with the oxidelayer 4604 and masked to remove the interface layer in regions where itis not desired in order to form a window exposing at least a portion ofthe oxide layer 4604. At block 4508, the process 4500 may involvebonding a handle, or replacement, wafer structure 4607 to at least aportion of the interface layer 4660, thereby forming a cavity 4675beneath at least a portion of the oxide layer 4604.

Certain embodiments disclosed herein provide for wafer-level cavitycreation below, for example, one or more passive elements of an SOIdevice with in combination with a substrate contact layer. Suchprocesses may involve using dual layer transfer.

FIG. 79 shows a process 4700 that can be implemented to form one or morecavities in an SOI device or structure having one or more features asdescribed herein. FIGS. 79 and 80 relate to cavity creation in adual-layer transfer process in conjunction with a substrate contactlayer. FIG. 80 shows examples of various stages of the fabricationprocess of FIG. 79. In the examples of FIGS. 79 and 80, it will beunderstood that the various blocks, or stages, may or may not beperformed in the example sequences illustrated. Furthermore, various ofthe illustrated/described steps may be omitted in certain embodiments,or additional steps may be implemented that are not explicitly describedwhile remaining within the scope of the present disclosure. Certain ofthe features illustrated in FIG. 80 may be similar in certain respectsto certain features illustrated in figures described above, andtherefore, for simplicity, detailed description of such features may notbe provided here.

At block 4702, the process 4700 involves providing at least a portion ofa SOI wafer having one or more devices and/or connections formed orotherwise associated therewith, as described in various embodimentsabove. At block 4704, the process 4700 involves removing some or all ofthe backside substrate 4806, which may expose at least a portion of theoxide layer 4804 on the backside of the wafer, and further applying asubstrate contact layer 4815. The substrate contact layer 4815 may be aconductive blanket or patterned layer or plate.

At block 4706, the process 4700 involves applying an interface layer4860 on the backside of the wafer, such as in contact with the oxidelayer 4804. The process further involves masking the interface layer4860 to form a window 4874 exposing at least a portion of the oxidelayer 4804. In certain embodiments, the substrate contact layer 4815 isat least partially exposed inside the window 4874 of the interface layer4860. That is, certain embodiments disclosed herein may take advantageof exposure to an oxide layer to pattern a contact material to providebackside connectivity. Hermetic sealing may advantageously exist betweenthe substrate contact layer 4815 and the interface material/layer 4860to allow for the cavity 4875 to be a vacuum cavity in some embodiments.

At block 4708, the process 4700 may involve bonding a handle, orreplacement, wafer structure 4807 to at least a portion of the interfacelayer 4860, thereby forming a cavity 4875 beneath at least a portion ofthe oxide layer 4804. In certain embodiments, at least a portion of thesubstrate contact layer 4815 is exposed within the cavity 4875.

Although not illustrated in FIGS. 70A and 70B or described above inconnection therewith or with respect to FIGS. 69A and 69B, a substratecontact layer similar to that shown in FIG. 80 may be utilized inconnection with such embodiments, or in other embodiments disclosedherein. For example, a substrate contact layer may be disposed at leastpartially in contact with the oxide layer 3804 shown in FIG. 70A,wherein at least a portion of the substrate contact layer is exposedwithin the cavity 3875 shown in FIG. 70B.

Certain of the embodiments disclosed above are suitable for layertransfer processes, where an interface layer is used to bond one waferto another. Conversely, certain other embodiments may rely on relativelyexpensive substrates engineered specifically to lower parasiticcapacitance and improve linearity. Cavity creation within the interfacelayer of a layer-transfer process can provide certain benefits, asdescribed herein.

FIGS. 81A-81C show embodiments of die structures 4900A, 4900B, 4900Cthat include generally rectangular-shaped cavities 4975A, 4975B, 4975C.FIG. 81A shows an embodiment of a die structure 4900A that includes aplurality of cavities 4975A formed in substantially geometricallyalignment over at least portions of RF core and energy management (EM)core regions of the die 4900A.

FIG. 81B shows an embodiment of a die wherein cavities 4975 are arrangedto cover at least a portion of an RF core region of the die, while an EMcore portion of the die is substantially free of cavities in at leastcertain regions thereof. In the embodiment of FIG. 81C, cavities 4975Cmay be arranged in clusters (e.g., cluster 4977), which may bepositioned around, or at least partially overlapping with, certaindevices that are desired to be isolated to some degree.

While generally rectangular-shaped cavities are illustrated in FIGS.81A-81C, it should be understood that cavities of any shape orconfiguration may be implemented within the scope of the presentdisclosure. FIGS. 82A-82C show embodiments of die structures 5000A,5000B, 5000C that include generally hexagonally-shaped cavities 5075A,5075B, 5075C. FIG. 82A shows an embodiment of a die structure 5000A thatincludes a plurality of cavities 5075A formed in substantiallygeometrically alignment over at least portions of RF core and energymanagement (EM) core regions of the die 5000A.

FIG. 82B shows an embodiment of a die wherein cavities 5075 are arrangedto cover at least a portion of an RF core region of the die, while an EMcore portion of the die is substantially free of cavities in at leastcertain regions thereof. In the embodiment of FIG. 82C, cavities 5075Cmay be arranged in clusters (e.g., cluster 5077), which may bepositioned around, or at least partially overlapping with, certaindevices that are desired to be isolated to some degree.

Examples of Implementations in Products

Various examples of FET-based circuits and bias/coupling configurationsdescribed herein can be implemented in a number of different ways and atdifferent product levels. Some of such product implementations aredescribed by way of examples.

Semiconductor Die Implementation

FIGS. 83A-83D schematically show non-limiting examples of suchimplementations on one or more semiconductor die. FIG. 83A shows that insome embodiments, a switch circuit 820 and a bias/coupling circuit 850having one or more features as described herein can be implemented on adie 800. Certain of the switch and/or bias/coupling circuitry may bedesigned as to be isolated by one or more cavities formed according toone or more embodiments disclosed herein. FIG. 83B shows that in someembodiments, at least some of the bias/coupling circuit 850 can beimplemented outside of the die 800 of FIG. 83A.

FIG. 83C shows that in some embodiments, a switch circuit 820 having oneor more features as described herein can be implemented on a first die800 a, and a bias/coupling circuit 850 having one or more features asdescribed herein can be implemented on a second die 800 b. FIG. 83Dshows that in some embodiments, at least some of the bias/couplingcircuit 850 can be implemented outside of the first die 800 a of FIG.83C.

Packaged Module Implementation

In some embodiments, one or more die having one or more cavity featuresdescribed herein can be implemented in a packaged module. An example ofsuch a module is shown in FIGS. 84A (plan view) and 84B (side view).Although described in the context of both of the switch circuit and thebias/coupling circuit being on the same die (e.g., example configurationof FIG. 84A), it will be understood that packaged modules can be basedon other configurations.

A module 810 is shown to include a packaging substrate 812. Such apackaging substrate can be configured to receive a plurality ofcomponents, and can include, for example, a laminate substrate. Thecomponents mounted on the packaging substrate 812 can include one ormore dies. In the example shown, a die 800 having a switching circuit820 and a bias/coupling circuit 850 is shown to be mounted on thepackaging substrate 812. The die 800 can be electrically connected toother parts of the module (and with each other where more than one dieis utilized) through connections such as connection-wirebonds 816. Suchconnection-wirebonds can be formed between contact pads 818 formed onthe die 800 and contact pads 814 formed on the packaging substrate 812.In some embodiments, one or more surface mounted devices (SMDs) 822 canbe mounted on the packaging substrate 812 to facilitate variousfunctionalities of the module 810.

In some embodiments, the packaging substrate 812 can include electricalconnection paths for interconnecting the various components with eachother and/or with contact pads for external connections. For example, aconnection path 832 is depicted as interconnecting the example SMD 822and the die 800. In another example, a connection path 832 is depictedas interconnecting the SMD 822 with an external-connection contact pad834. In yet another example a connection path 832 is depicted asinterconnecting the die 800 with ground-connection contact pads 836.

In some embodiments, a space above the packaging substrate 812 and thevarious components mounted thereon can be filled with an overmoldstructure 830. Such an overmold structure can provide a number ofdesirable functionalities, including protection for the components andwirebonds from external elements, and easier handling of the packagedmodule 810.

FIG. 85 shows a schematic diagram of an example switching configurationthat can be implemented in the module 810 described in reference toFIGS. 84A and 84B. In the example, the switch circuit 820 is depicted asbeing an SP9T switch, with the pole being connectable to an antenna andthe throws being connectable to various Rx and Tx paths. Such aconfiguration can facilitate, for example, multi-mode multi-bandoperations in wireless devices.

The module 810 can further include an interface for receiving power(e.g., supply voltage VDD) and control signals to facilitate operationof the switch circuit 820 and/or the bias/coupling circuit 150. In someimplementations, supply voltage and control signals can be applied tothe switch circuit 120 via the bias/coupling circuit 850.

Wireless Device Implementation

In some implementations, a device and/or a circuit having one or morefeatures described herein can be included in an RF device such as awireless device. Such a device and/or a circuit can be implementeddirectly in the wireless device, in a modular form as described herein,or in some combination thereof. In some embodiments, such a wirelessdevice can include, for example, a cellular phone, a smart-phone, ahand-held wireless device with or without phone functionality, awireless tablet, etc.

FIG. 86 schematically depicts an example wireless device 900 having oneor more advantageous features described herein. In the context ofvarious switches and various biasing/coupling configurations asdescribed herein, a switch 120 and a bias/coupling circuit 150 can bepart of a module 810. In some embodiments, such a switch module canfacilitate, for example, multi-band multip-mode operation of thewireless device 900.

In the example wireless device 900, a power amplifier (PA) module 916having a plurality of PAs can provide an amplified RF signal to theswitch 120 (via a duplexer 920), and the switch 120 can route theamplified RF signal to an antenna. The PA module 916 can receive anunamplified RF signal from a transceiver 914 that can be configured andoperated in known manners. The transceiver can also be configured toprocess received signals. The transceiver 914 is shown to interact witha baseband sub-system 910 that is configured to provide conversionbetween data and/or voice signals suitable for a user and RF signalssuitable for the transceiver 914. The transceiver 914 is also shown tobe connected to a power management component 906 that is configured tomanage power for the operation of the wireless device 900. Such a powermanagement component can also control operations of the basebandsub-system 910 and the module 810.

The baseband sub-system 910 is shown to be connected to a user interface902 to facilitate various input and output of voice and/or data providedto and received from the user. The baseband sub-system 910 can also beconnected to a memory 904 that is configured to store data and/orinstructions to facilitate the operation of the wireless device, and/orto provide storage of information for the user.

In some embodiments, the duplexer 920 can allow transmit and receiveoperations to be performed simultaneously using a common antenna (e.g.,924). In FIG. 86, received signals are shown to be routed to “Rx” paths(not shown) that can include, for example, a low-noise amplifier (LNA).

A number of other wireless device configurations can utilize one or morefeatures described herein. For example, a wireless device does not needto be a multi-band device. In another example, a wireless device caninclude additional antennas such as diversity antenna, and additionalconnectivity features such as Wi-Fi, Bluetooth, and GPS.

General Comments

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” The word “coupled”, as generally usedherein, refers to two or more elements that may be either directlyconnected, or connected by way of one or more intermediate elements.Additionally, the words “herein,” “above,” “below,” and words of similarimport, when used in this application, shall refer to this applicationas a whole and not to any particular portions of this application. Wherethe context permits, words in the above Description using the singularor plural number may also include the plural or singular numberrespectively. The word “or” in reference to a list of two or more items,that word covers all of the following interpretations of the word: anyof the items in the list, all of the items in the list, and anycombination of the items in the list.

The above detailed description of embodiments of the invention is notintended to be exhaustive or to limit the invention to the precise formdisclosed above. While specific embodiments of, and examples for, theinvention are described above for illustrative purposes, variousequivalent modifications are possible within the scope of the invention,as those skilled in the relevant art will recognize. For example, whileprocesses or blocks are presented in a given order, alternativeembodiments may perform routines having steps, or employ systems havingblocks, in a different order, and some processes or blocks may bedeleted, moved, added, subdivided, combined, and/or modified. Each ofthese processes or blocks may be implemented in a variety of differentways. Also, while processes or blocks are at times shown as beingperformed in series, these processes or blocks may instead be performedin parallel, or may be performed at different times.

The teachings of the invention provided herein can be applied to othersystems, not necessarily the system described above. The elements andacts of the various embodiments described above can be combined toprovide further embodiments.

While some embodiments of the inventions have been described, theseembodiments have been presented by way of example only, and are notintended to limit the scope of the disclosure. Indeed, the novel methodsand systems described herein may be embodied in a variety of otherforms; furthermore, various omissions, substitutions and changes in theform of the methods and systems described herein may be made withoutdeparting from the spirit of the disclosure. The accompanying claims andtheir equivalents are intended to cover such forms or modifications aswould fall within the scope and spirit of the disclosure.

What is claimed is:
 1. A method for fabricating a semiconductor device,the method comprising: providing a transistor device formed over anoxide layer formed on a semiconductor substrate; removing at least partof the semiconductor substrate; applying an interface material below toat least a portion of the oxide layer; removing a portion of theinterface material to form a trench; and at least partially covering theinterface material and the trench with a substrate layer to form acavity.
 2. The method of claim 1 further comprising applying a substratecontact layer to at least a portion of a backside of the oxide layer,the substrate contact layer being at least partially exposed in thecavity after said at least partially covering the interface material andthe trench.
 3. The method of claim 2 wherein the substrate contact layeris electrically coupled to the transistor device via a through-oxidevia.
 4. The method of claim 1 further comprising removing a handle waferfrom a top-side of a passivation layer disposed above the transistordevice.
 5. The method of claim 4 wherein the passivation layer is one ofone or more dielectric layers formed over electrical connections to thetransistor device.
 6. The method of claim 1 wherein the trench is atleast partially below the transistor device.
 7. The method of claim 1wherein the trench is at least partially below an electrical devicecoupled to the transistor device via one or more electrical connectionsformed in one or more dielectric layers formed over the transistordevice.
 8. The method of claim 1 wherein said removing the portion ofthe interface material involves etching away the portion of theinterface material.